This is a very easy dish to make.
Coat fish lightly with olive oil and lay in a shallow baking dish. Put in a 350F oven to bake. While fish is cooking, saute onion until translucent, add garlic, tomatoes, and olives and cook just until tomatoes collapse. Just before fish is done, top with crumbled feta and cook just until cheese softens/melts. Serve with vegetables of your choice.
Say Bismillah and eat!