Watermelon Rind Sour Curry - Gang Som Pleug Tang Mo แกงส้มเปลือกแตงโม

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I didn't grow up eating Watermelon Rind Sour Curry and I wish I did because it's so good and so accessible. I'd heard of Watermelon Rind Sour Curry from a friend and decided to give it a try. My family loves it. Now when we buy a watermelon, a Watermelon Rind Sour Curry is expected.

The watermelon rind works so well absorbing spices and strong flavors in the sour curry. The dense texture keeps the rind from falling apart during cooking. With mild flavor, the rind absorbs and tone down the sharp spices and flavor. Every bite of the watermelon rind is full of flavor.

Gang Som or sour curry is more common at a Thai's dining table than red or green curries. It uses core Thai ingredients, shallots, shrimp paste, dried peppers, tamarind and fish. No need for coconut milk. It's extremely easy to make and can last several days. Several types of vegetables and vegetable combinations are common such as yardlong beans and daikon, Chinese water spinach, drum sticks, green beans, green papaya, bean sprouts and napa cabbage. Adding shrimp or big chunks of fish is also a favorite of restaurants as a way to give oomph to the homey curry.

The term 'som' has 3 meanings: orange as in the fruit, orange as color and a sour taste. In this case, som is an old term referring to the sour taste. If you ever run into a recipe for 'gang som' and it calls for an orange, please note that something was lost in the translation.

Sour Curries are native to central Thailand. The south has their version which includes fresh turmeric and seafood. Try a Southern Sour Curry, it's another of my favorite dishes.

4 Servings, Prep Time: 25 Minutes, Total Time: 25 Minutes

4 cups water
2-3 ounces white fish
3 tablespoons Sour Curry Paste
2-3 cups Watermelon Rind
1 tablespoon tamarind paste
1-2 tablespoons fish sauce
1/2 teaspoon sugar

Tips and Techniques

I often find that I fish out the veggies in sour curry and leave a lot of broth at the end. I recommend have more watermelon rind ready when you find yourself with just leftover broth. Add the watermelon rind to stretch the curry.
You can use more or less fish than what's called for. I sometimes use leftover fish from another dish.
Any white flesh fish works for this dish. In Thailand, a snakehead murrel(ปลาช่อน) is the fish commonly used in sour curry.
Adding sugar is optional. If you do, add just enough to round out the sharp flavor but not enough to taste the sweetness.
You can always add more water if you feel that the flavor is stronger than what you like.

Method

Prepping

Slice the hard green skin off the watermelon rind. Cut the watermelon rind into bite size pieces, ¾ of inch by 1 inch.

Sour curry paste is so simple that most people don't buy it but make it right before they make the curry. The core ingredients in sour curry are dried chili peppers, shallots and shrimp paste. See our Homemade Sour Curry Paste.

Cooking

Boil the water in a pot big enough for 8 cups. When the water boils, drop the fish in. Let the fish cook for a minute or 2 until it turns white. No need to wait until the water boils again. We just need to cook the fish. Scoop out the fish and drop it in the mortar. Do not discard the water. Keep the water simmer while you pound the fish.

Pound the fish with sour curry paste. As you pound the fish, you may see bones, pick them out. When the fish is finely ground, scoop out the mixture into the pot. Let it dissolve in the boiling water. The broth should turn bright orange instantly. The ground fish should disappear and thicken the broth. Drop the watermelon rind into the pot. Let it boil.

Add tamarind and fish sauce. Stir and make sure that the tamarind is completely dissolved. You can add the tamarind paste into a ladle with a little bit of hot broth for a quick dissolve.

Taste the broth. The broth should taste very strong, sharp sour and a bit salty. This strong flavor will disappear into the mild watermelon rind. If you decide to add sugar, add a scant ½ teaspoon to round out the sharpness of the tamarind. I don't add sugar to mine since I love it sour. If I cook for my mother, I have to add a tiny bit of sugar because she likes it that way. Most of the Thai restaurants would, too. And often, so much sugar is added that it ruins the dish for me.

Let the sour curry simmer for 10-15 minutes or until the rind is no longer crunchy. The rind should be soft but not mushy. It should turn translucent when cooked. The light green now looks a little orange from absorbing the broth. The bottom of the pot should appear pulpy from the ground fish and spices. Before serving, stir up the fish and spices on the bottom of the pot. Ladle into a large bowl or a hot pot.

Serve hot with rice.