Tamarind soup with shrimp, rice, and peas

This week I finally had an opportunity to attend a lecture in Harvard’s Science and Cooking series, which normally I wouldn’t be able to do due to classes (thank you Christopher Columbus for the day off?). For those who don’t know, it’s a series of public lectures in which a member of Harvard’s science faculty begins by explaining a scientific principle relevant to cooking, then a distinguished chef comes in and demonstrates the concept. As if this weren’t already awesome enough, videos of many of the lectures are available on YouTube. The lecture I went to was about heat transfer, followed by a demo from Raül Balam Ruscalleda of making picada de pescador, or the Catalunian version of a fisherman’s stew. Seeing, smelling, and tasting his soup of course made me want to try and recreate it on my own, but what really motivated me to do so was its simplicity and how he illuminated each seemingly basic step of making the stew in great detail.

Although Ruscalleda’s version relied on a tomato and lobster stock filled with lobster meat and rice, I decided to apply his technique to a very Thai recipe. For the most part, I followed the list of ingredients for Gang Som, a sour curry, but cooked it according to his method. I think this is one of the best things I’ve ever made – a wonderful balance of sour and spicy, the sort of clear yet potent soup that makes the cold weather blues go away. I’m including a recipe here, but all of the measurements are very approximate.

Fisherman’s Gang Som

For the soup base:

5 red Fresno chiles, roughly chopped

10 bird’s eye chiles, roughly chopped

12 cloves of garlic, smashed

1 small onion, chopped*

2 shallots, chopped*

1 tablespoon shrimp paste

1 tablespoon cilantro stems**

Everything else

1 lb. extra large shrimp with shells on***

7 tablespoons tamarind paste****

1/4 cup fish sauce

A big splash of dry sherry

1 oz. palm sugar

1.5 cups rice*****

1 cup frozen peas******

A large handful of cilantro leaves, chopped

Peel and devein the shrimp, tossing the shells into a large stock pot. Cover the shells with water, add a dash of salt, bring to a boil, then turn the heat down and let simmer for about 15 minutes. Chop the shrimp meat into large chunks and set aside.

While the shells are simmering, prepare the base. Combine all the base ingredients with a little water in a mortar and pestle or food processor until they have formed a paste. Add this to the shrimp shell stock with a little more salt and let simmer for another 15 minutes. Add water as necessary to keep the stock loose and soupy.

Once all the ingredients have softened and released their flavors into the stock, strain through a sieve with a fairly loose mesh or a colander – you want something that will catch all the shells but that will also allow some of the smaller vegetable particles to pass through. Add the tamarind, fish sauce, sherry, and palm sugar to the stock, then taste and add more water or salt until the stock reaches the right balance – you want something tart without being too overpowering. Add the rice, bring to a boil, then turn the heat down let simmer until the rice is almost cooked.

While the rice is cooking, heat a skillet with a little oil over medium high heat. Add the shrimp and sauté until just opaque but not entirely cooked. When the rice is almost ready, add the shrimp and peas to the soup. Turn the heat up and as soon as the soup starts to boil, remove from heat. Fold in the cilantro and serve.

* I caramelized the onions and shallots by simmering them with enough water to cover and a dash of canola oil for four hours, as Ruscalleda did. I’ve never encountered a Thai recipe that required softening the shallots, so I suppose it’s not necessary to include this step.

** Many Thai recipes call for cilantro roots to be used within the soup base. Finding cilantro with the roots attached is virtually impossible here in the northeast, so I opted for the stems instead.

*** Ruscalleda used lobster. He took the heads and bodies and lightly macerated them in a food processor before adding them to hot water to make stock. The claws and tails were reserved and their meat used as described in the last step.

**** I used a 7 oz. package of tamarind pulp soaked in 7 fl. oz of hot water that was then mixed together and passed through a sieve.

***** I used jasmine rice because it’s what I had on hand. Ruscalleda used some sort of hardy Italian rice similar to arborio, which I have a feeling would work better and would absorb less of the stock liquid.

****** My addition, although this soup could be made without peas or with another vegetable.

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