Microwave ovens work by shaking up the water and fat in food, which in turn, makes heat. Covering food with microwave-safe plastic wrap or putting it in a microwave-safe, covered casserole dish locks in steam. The combination of inside heating and outside steaming cooks items in less time than it would take otherwise.
Microwaving is particularly suited to cooking thin, skinless fillets of fish. Begin by arranging the fish in a single layer in a microwavable dish. Be sure to tuck slim pieces under, or overlap thin edges to ensure even thickness. This will prevent overcooked, tough ends. Moisten the fish with a small amount of seasoned liquid or broth, but do not submerge it completely. Microwave on full power or using the “fish” setting until the fish is mostly opaque and just begins to flake-about one and half to five minutes. Allow the fish to stand for a short time after microwaving to complete the cooking process.
This method works best when cooking small portions or when you don’t desire a browned exterior.