Line a well-greased 12- x 8- x 2-inch baking dish with onion slices. Rinse steaks thoroughly in cold water, and pat dry. Place steaks on top of onion. Combine remaining vegetables in a medium mixing bowl; spread over top of fish. Combine wine, lemon juice, salt, dill weed, and pepper in a small mixing bowl; pour over vegetables. Bake, uncovered, at 350° for 35 minutes or until fish flakes easily when tested with a fork.
Transfer fish and vegetables to a warm serving platter. Serve immediately with lime wedges.