Indian Crab Curry

Name: Indian Crab Curry
Prep time: 20 min
Cook time: 30 min
Total time: 50 min
Cuisine: Indian
Ingredients: 8 whole crabs (cooked); 1 1/2-inch piece tamarind; 1/2 cup hot water; 2 large onions (sliced); 2 large tomatoes (sliced); 10 dried red chilies (or fewer to taste); 2 tablespoons garlic paste; 1 tablespoon ginger paste; 1 1/2 cups grated coconut; 2 tablespoons coriander powder; 2 tablespoons cumin powder; 1/2 teaspoon turmeric powder; 1/2 teaspoon red chili powder; 2 green chilies (slit); 2 tablespoons cooking oil (vegetable, canola, or sunflower); 3 cups hot water (more or less for desired gravy); Salt (to taste)