Spicy Crab Curry - Bangla Style

2 fresh Dungeness crabs, cleaned and with their shells cracked

2 teaspoons ground turmeric

½ teaspoon salt

1 tablespoon mustard seed

1 tablespoon hot water

1 tablespoon mustard oil

3 cups sliced red onion

1 ¾ cups boiling potatoes, peeled, halved lengthwise, and cut crosswise into 1/4-inch slices

2 whole cloves

1 (1 inch) piece cinnamon stick

2 pods green cardamom pods

5 whole black peppercorns

2 large tomatoes, coarsely chopped

4 Thai green chiles

1 ½ teaspoons garlic paste

1 ½ teaspoons ginger paste

1 teaspoon cayenne pepper

salt to taste

1 teaspoon white sugar

1 wedge fresh lemon

½ cup chopped fresh cilantro

Rub the crabs with 1 teaspoon of the turmeric and 1/2 teaspoon salt; let them marinate for 1 hour. Combine the mustard seed and hot water in a small bowl and let stand for 10 minutes. Use a mortar and pestle to grind the seeds into a coarse paste.

Heat the oil in a wok or kadhai over medium heat. Add the crabs and stir fry until they change color, about 4 minutes. Remove the crabs from the oil and set aside.

Add the sliced onions to the wok and cook and stir over medium heat until the onions are translucent, about 5 minutes. Raise the heat to high, add the potatoes, and cook, stirring constantly, for about 2 minutes. Add the cloves, cinnamon stick, cardamom pods, and peppercorns, and stir for thirty seconds.

Stir in the tomatoes, ginger paste, and garlic paste. Halve three of the chiles and add them to the wok. Cook and stir for an additional minute or two over high heat. Reduce the heat to medium; add the remaining 1 teaspoon turmeric, the cayenne pepper, and the mustard paste and stir to combine. Add the crabs to the wok and pour in just enough water to cover the vegetables. Bring the water to a boil and stir in the sugar and salt to taste.

Cover the wok, reduce the heat, and simmer until the potatoes are tender and the water is reduced by half, about 10 minutes. Remove the lid, stir, and simmer until the gravy is thickened, about 5 minutes more.

Squeeze the lemon wedge over the finished dish. Garnish with chopped cilantro and sliced green chile and serve hot, with rice.