Goan curried-fish stew

2 pounds sole fillets, cut into 1-inch pieces
1/4 cup lemon juice (from about 1 lemon)
1 1/4 teaspoons Salt
2 Cloves Garlic, smashed
4 teaspoons chopped fresh Ginger
1 cup canned unsweetened coconut Milk
1 tablespoon ground coriander
1 teaspoon ground Cumin
1 teaspoon Brown sugar
1/2 teaspoon fresh-ground black Pepper
1/4 teaspoon turmeric
1/8 teaspoon cayenne pepper
3 tablespoons cooking oil
1 onion, chopped
1 tomato, chopped
4 jalapeño peppers, seeds and ribs removed, minced
3/4 cup water

1. In a glass or stainless-steel container, combine the sole, lemon juice, and 1/2 teaspoon of the salt. Let marinate at least 10 minutes.
2. In a blender, puree the Garlic and Ginger with the coconut Milk, coriander, Cumin, Brown sugar, black Pepper, turmeric, and cayenne.
3. In a large saucepan, heat the oil over moderate heat. Add the onion; cook, stirring occasionally, until golden, about 5 minutes. Add the tomato and cook, stirring occasionally, until soft, about 5 minutes. Add the coconut mixture, the jalapeños, the water, and the remaining 3/4 teaspoon Salt and bring slowly almost to a simmer, stirring frequently.
4. Add the fish and 1 tablespoon of the marinade. Bring to a simmer and continue simmering until the fish is just done, 1 to 2 minutes.