Sprinkle fillets with salt and pepper. In a large skillet coated with cooking spray, cook fillets in butter over medium-high heat until lightly browned, 2-3 minutes on each side.
Transfer fish to a broiler pan or baking sheet; top with tomato.Combine topping ingredients; spoon over the tomato slices.
Broil 3-4 in. from the heat until topping is lightly browned and fish just begins to flake easily with a fork, 2-3 minutes.