1/2 cup vegetable oil for frying
3 pounds cod fillets, cut into 2 to 3 ounce portions
salt to taste
2 large onions, peeled and sliced into rings
2 cloves garlic, chopped
8 whole black peppercorns
4 whole allspice berries
3 bay leaves
1 red chile pepper, seeded and sliced lengthwise
2 cups red wine vinegar
1/2 cup water
1/2 cup packed brown sugar, or to taste
2 tablespoons curry powder
1 teaspoon ground turmeric
2 teaspoons ground cumin
2 teaspoons ground coriander
Heat the oil in a large skillet over medium-high heat. Season the fish with salt and place in the skillet. Fry on both sides until fish is browned and cooked through, about 5 minutes per side. Remove from the skillet and set aside.
Fry the onions and garlic in the same skillet over medium heat until translucent. Add the peppercorns, allspice berries, bay leaves, and red chile pepper. Pour in the vinegar and water and bring to a boil. Stir in the brown sugar until dissolved. Season with curry powder, turmeric, cumin and coriander. Taste and adjust the sweetness if desired.
Layer pieces of fish and the pickling mixture in a serving dish. Pour the liquid over until the top layer is covered. Allow to cool then cover and refrigerate for at least 24 hours before serving.