Heat the oven to 325Â°F.
Combine the mustard, salt, garlic, and cumin seeds.
Place the bass into a foil-lined, greased baking pan and pour the mustard sauce over it.
Add the tomatoes, cover, and bake for 20-30 minutes, or until the fish is done but not overcooked and dry.
Serve with lemon wedges and Basmati Pilaf or new potatoes.