Spray Pam on a shallow baking dish and arrange the fillets (skin sides down) that have been seasoned with salt. Bake for 10 minutes, uncovered.
In the meantime, heat oil on a frying pan, and sauté the red onion and red bell pepper for a few minutes. When slightly tender, add the tomatoes, green olives, garlic, thyme, and black pepper. Cook a few minutes until of desired consistency and add lemon juice and cumin to mix well.
Place this mixture on top of fish, and continue baking the fish for 10-15 minutes longer, until it flakes easily with a fork.