Category Archives: Soups

Chilled Avocado Soup

The avocado is a favorite PHD ingredient: it is a fatty subtropical fruit with a fatty acid profile similar to that of olive oil (only about 14% omega-6). Native to the Americas, its wild ancestor, a small, black-skinned berry, is still found in southern Mexico and Central America. The avocado has been cultivated since at least 10,000 BC, making it one of the first domesticated plants in the Americas. After the European colonization of America, it spread slowly: Wikipedia says it was introduced to Indonesia in 1750, Brazil in 1809, South Africa and Australia in the late 1800s, and the Levant only in 1908.

Like all agricultural crops, the avocado has undergone extensive breeding. Over 80% of supermarket avocados are Hass avocados, which descend from a single “mother tree” on the La Habra Heights, California farm of mail carrier Rudolph Hass. Hass patented his tree in 1935.

In addition to their excellent (grade B in our book) fatty acid profile, avocados are nutritious. They have 35% more potassium per unit weight than bananas, a diverse range of vitamins and minerals, and are fiber-rich: 78% of the carbohydrate in avocados is fiber, totaling 7 g of fiber per 100 g serving.

This chilled avocado soup is a great summer food. Because it is so fatty, it is best paired with low-fat foods, such as a white fish like halibut or cod, shellfish, and potatoes.

Here is the recipe. Happy holiday weekend, everyone!

Food for a Fast

Alfredo asked us to offer ideas for how to fast during Lent:

What to eat during fasting (other than cranberries & coconut oil) is on my mind. Looking for some variation in the fasting menu.

It’s a great question. We did have a post on one possible fasting food – Neo-Agutak: “Eskimo Ice Cream” – but never discussed alternatives or the reasons for eating particular foods during a fast.

Fasts don’t have to be food-free

Some people think a fast should involve no food at all. On the Neo-Agutak post, Don Matesz commented:

I would not say that I was fasting if I consumed more than 625 calories during any period of that “fast.”

But that’s not the position of the Catholic Church. During Lent, Ash Wednesday and Good Friday are fast days. The US bishops allow one full meal and up to two snacks:

The law of fasting requires a Catholic from the 18th Birthday (Canon 97) to the 59th Birthday (i.e. the beginning of the 60th year, a year which will be completed on the 60th birthday) to reduce the amount of food eaten from normal. The Church defines this as one meal a day, and two smaller meals which if added together would not exceed the main meal in quantity. Such fasting is obligatory on Ash Wednesday and Good Friday. The fast is broken by eating between meals and by drinks which could be considered food (milk shakes, but not milk).

Children, the elderly, and those whose health might be threatened are exempt from the requirement to fast.

So let’s consider a fast to be any period of reduced calorie consumption – not zero food.

Basic fasting: Electrolyte and fluid replacement

It is certainly a mistake to consume nothing at all during a fast.

People deprived of fluids and electrolytes die quickly. In a famous case cited in Wikipedia (“Starvation”), Drusus Caesar, son of Agrippina the Elder, was starved to death in 33 AD by the emperor Tiberius, and managed to stay alive for nine days only by chewing the stuffing of his bed. When Saint Maximilian Kolbe and nine others were starved in Auschwitz, seven of the ten died within two weeks.

When fluids are provided, however, survival can be much longer. Even in his 60s, Gandhi was able to go without food for 21 days. In the Irish hunger strikes of 1980-1981, no one who fasted less than 46 days died, and about half those who fasted between 46 and 73 days died.

So fluids and electrolytes extend the duration of a fast by about a factor of four. Since we want our fasts to be safe and health-improving, we should certainly take:

  • Water.
  • Sodium and chlorine. During a fast protein is converted to glucose and ketones, releasing nitrogen waste in the form of urea. Sodium and chloride are excreted along with the urea. Salt loss can be fairly rapid during a fast, equivalent to as much as a teaspoon of salt a day. A large amount of water is lost along with it.
  • Potassium. Potassium is the intracellular electrolyte, sodium the extracellular, and osmotic pressure must be balanced. So potassium will be lost along with water and sodium, and should be replenished with it.
  • Calcium and magnesium. These also serve electrolytic functions and it is desirable to maintain their concentrations.
  • Acids. These are beneficial for the digestive tract and metabolism, and also for solubilization of minerals. Citrate, for instance, helps prevent kidney and gallstones.

Vegetables are the best source of potassium; bone broth is a source of calcium and magnesium. The best acids are citrus juices, such as lemon juice, and vinegars, such as rice vinegar. Sea salt, or salty flavorings such as soy sauce or fish sauce, can provide sodium chloride. So the most basic food to take during a fast is a soup made of vegetables in bone broth, with salt and an acid added.

Here are some pictures. First, make up a bone broth by cooking bones in acidified water:

It’s best to use a ceramic or enameled pot to prevent leaching of metals from the pot.

When you’re ready to eat, put some scallions or celery and cilantro or basil in a bowl, and add hot broth:

Add salt, pepper, acid, and spices to taste.

Spinach and tomatoes are great vegetables for these broths, because they are rich in potassium. Here is a tomato soup:

Here’s a slightly fancier example. I think this had tomatoes, onions, peppers, carrots, and kohlrabi:

Served with parsley and scallions, rice vinegar, and sea salt:

Adding some food

So far we haven’t provided any calories to speak of. The next step in reducing the stress of the fast is to add some nutrition to the soup.

The stress of a fast is largely due to the absence of dietary carb and protein. The body has limited carb storage – glycogen is depleted early in a fast – and is loath to cannibalize lean tissue for protein. On the other hand, the body has abundant fat reserves. So

Two strategies may make sense in different circumstances:

  • A protein-sparing modified fast. Protein, which is convertible to glucose, is eaten to relieve the carb+protein deficit.
  • A ketogenic fast. Short-chain and medium-chain fatty acids, such as are found in coconut oil, are eaten to generate ketones. Ketones can partially substitute for glucose utilization.

What these have in common is that they reduce the carb+protein.

Probably 90% of people who fast should favor the protein-sparing approach. Those on ketogenic diets for neurological disorders should probably favor the ketogenic fasting approach.

An example of a food suitable for a ketogenic fast would be Neo-Agutak: “Eskimo Ice Cream” (Dec 5, 2010).

A suitable food on a protein-sparing modified fast would supply most calories as protein; carb and fat calories would be from nutrient-dense sources. Egg yolks, which are rich in phospholipids like choline, and potatoes are good examples of nutrient-dense fat and carb sources.

The easy way to implement this healthy fast: just add eggs, potatoes, and maybe some fish or shellfish (which tend to be protein-rich, and comply with the Catholic guidelines for Friday abstinence) to any of the soups shown above. Heat the soup in the microwave and there you have it: a healthy fast-day meal!


Those on weight loss diets will notice that by adding protein, carbs, and a few nourishing fats to our fast-day soup, we’re getting very close to our recommended diet for calorie-restricted weight loss diets: see Perfect Health Diet: Weight Loss Version (Feb 1, 2011).

There’s a good reason for that: both posts work from the same design principles. Both aim at the greatest possible nourishment on the fewest calories.

Would you like to lose weight? Consider making these nourishing soups a staple of your diet.

Even if you’re not fasting or trying to lose weight, consider making these soups a regular part of your daily meals. It’s very easy to make a broth on the weekend and warm it up and pour it over diced vegetables at mealtime. You might find them a very satisfying addition to your diet.

Tom Kha Shrimp and Scallop (Thai Soup)

We recommend making bone broths regularly, for the minerals and collagen extracted from the bone and joint tissue. The broths can be drunk as a beverage, used in cooking (eg in making rice), and used as the base for soups, curries, and stews.

We make broth most Saturdays, and use it throughout the week. For an example of how to make broth, see Bone Broth Revisited; and Pumpkin Soup, Oct 3, 2011. The nature of the broth depends on the type of bones you get. Marrow bones create a fattier broth; bones with joint tissue attached create a collagen-rich gelatin; bare bones create a mineral-rich watery broth. If you start with marrow and joint bones, then the first broth will have all the fat, the first and second will have a lot of collagen, and later batches will become progressively more watery.

Since broth itself has a mild taste, it can be the foundation for a great diversity of soups. Once you have broth, most soups can be made very quickly – often in 10 minutes.

Tom Kha Gai, or chicken galangal soup, is a classic dish of Thai cuisine. It’s always made with coconut milk and usually lemongrass (which has a mild citrus flavor) and some kind of spicy flavor.

Of course, there’s no need to use chicken, and we generally prefer seafood, ruminant meats, eggs, and even duck to chicken. In today’s recipe, we used shrimp and scallops as our meats.


We used coconut milk, bone broth (not shown), shrimp, scallops, cilantro (coriander leaves), lemongrass, lime juice, fish sauce (not shown), mushrooms, and in the small bowl on the right, a homemade chili paste, galangal root, and sliced Serrano or Jalapeno chili peppers.


Place equal parts coconut milk and bone broth in a pot; add lemongrass, sliced galangal, lime juice, and 1 tbsp fish sauce:

You won’t eat the lemongrass, so it’s best to slice it in long diagonal strips that are easy to find and remove from the finished soup. Don’t cut it too small.

Bring the soup to a simmer for 5 minutes and add the remaining ingredients. Mushrooms, chili paste, and peppers:

Simmer another 5 minutes, and add shrimp and thin-sliced scallops:

The shrimp and scallops only need 2-3 minutes, so it’s almost done. Add cilantro:

It only takes a few minutes until everything is cooked, and it’s ready to serve:


Many variations are possible to alter the taste. Chili powder can be substituted for the paste, and ginger root for galangal. The lime juice can be used for the citrus flavor in place of lemongrass. Add more fish sauce for a saltier taste, or more lime juice for sourness.

Tom Kha Gai has always been one of our favorite soups, and it’s very easy to make. It’s even better with scallops and shrimp!

Bone Broth Revisited; and Pumpkin Soup

We’d like to thank Shilpi and Amit Mehta for hosting the potluck dinner last night. My talk was on “Common Pitfalls of Paleo,” and it was a pleasure to meet so many Paleo enthusiasts, including people we knew from PaleoHacks, email, comments, and Facebook.

We brought pumpkin soup to the potluck, and that will be our food post this week. But we’ve had some questions about bone broths, so let’s revisit that first.

Making a Tasty Broth

Earlier, we discussed making a broth from ox feet (Ox Feet Broth, Miso Soup, and Other Soups, Jan 2, 2011). The advantage of feet (ox feet, chicken feet) or tails (ox tail) is that they have a lot of connective tissue, so they make a gelatinous broth full of nourishing collagen.

However, you can make a good broth from any bones, and it’s possible to find marrow bones that also have some connective tissue. With longer cooking, you can extract collagen and minerals from the bone itself, and get a good broth from these larger bones.

We’ve found, on limited data so far, that bones from grass-fed animals from local farms seem to produce a tastier broth than supermarket bones. I’d be curious to hear if others have had the same experience.

A few other tricks can help make a tasty broth. One tactic that seems to work is to discard and replace the cooking water at an early stage.

Here’s what we do. In this case, we started with a mix of beef and pork bones:

As you can see some blood comes out of the bones, especially the pork bones, almost immediately. This may be responsible for the poor taste some experience.

We put the heat on very low and let the water warm up gradually. Before it reaches a boil, after an hour or less, it looks like this:

At this point we drain and discard the liquid, adding new water. It now looks like:

You can see the marrow inside the pork bones, which will fall out before we’re done, and the ligaments and tendons in the joints, which will produce a nourishing gelatin. Bits of meat and fat will also be released.

After some hours of cooking, all the meat and fat and most of the marrow and connective tissue will have fallen off the bones. It will look something like this:

At this point you can pour out the broth into a container and use this fatty, meaty broth for rich soups. Seaweed, vegetables like tomatoes and onions, and thinly sliced beef, tendon, or pork bellies go well with this broth. We often use it for Pho (Vietnamese Noodle Soup) (Feb 27, 2011).

Add water and acid and continue cooking. This second round of broth will mainly contain minerals and some collagen, and will need longer cooking.

In the second and later rounds of cooking, we add an acid to help extract minerals from the bones and expose the collagen matrix. Lime juice, lemon juice, and vinegar all work well. We especially like the juice of a lime, and rice vinegar, which gives a slightly sweet taste; others seem to like apple cider vinegar, which is more acidic.

Here are our beef and pork bones early in the process:

And here they are later:

The bones will be obviously softening by this point, as you can tell by poking them with the tine of a fork.

If you wish, you can once again collect the broth, add new water and cook again. Every successive broth will be lighter. In the third round, with long enough cooking, the broth becomes white, like this:

I have heard that in earlier times, when food was costly but fuel cheap, that bones would get cooked until all the nutrients had been extracted – for as long as a month.

Pumpkin Soup

Pumpkins are abundant in New England in October, and we love pumpkin soup.

Here are the ingredients – garlic, onion, and pumpkin:

On very low heat, gently cook the garlic and onion in 3 tbsp butter:

Then add the diced pumpkin and enough bone broth to cover:

Bring to a simmer but don’t boil. When the pumpkin is cooked, after about 20 minutes, use a hand blender to puree the pumpkin-onion-broth mixture in the pot. It will look like this:

Add salt, pepper, cinnamon, and nutmeg to taste, and 1 tbsp rice syrup for a touch of sweetness. Add curry, or other spices, if you like a more flavorful soup. Serve hot, adding a dollop of sour cream if you like a richer, fattier taste:

A delicious autumn appetizer! It can even serve as a meal by adding meat and vegetables to the soup.