Fish Baked with Tomatoes and Spices (Mtuzi Wa Samaki ? Kenya)

1 large onion, sliced
2 cloves garlic, chopped
2 jalape?o peppers, seeded and chopped
2 tablespoons vegetable oil
1 (16 ounce) can whole tomatoes, drained and chopped
2 tablespoons vinegar
1 1/4 teaspoons ground cumin
3/4 teaspoon ground coriander
1/2 teaspoon salt
4 halibut steaks, 1 inch thick (about 2 pound)
Fresh cilantro, snipped (optional)

Cook and stir onion, garlic and peppers in oil in 10-inch skillet over medium heat until onion is tender. Reduce heat; stir in remaining ingredients except fish. Cook uncovered over low heat, stirring occasionally, 5 minutes.

Arrange fish in ungreased 12 x 7-inch baking dish. Spoon tomato mixture over fish. Bake uncovered at 355 degrees F until fish flakes easily with fork ? 25 to 30 minutes. Sprinkle with snipped fresh cilantro if desired.