Pre-heat oven to 425°F (220°C).
In a bowl, mix the mustard, mayonnaise, green onion and coriander.
Cover the cooking tray with lightly oiled aluminum paper. Place salmon filets on the tray and season with salt and pepper.
Spread an even layer of the mayonnaise mix over the filets.
In a small bowl, mix the butter and Panko. Sprinkle the Panko mixture over the salmon and tamp it lightly so it sticks to the topping.
Cook in pre-heated oven for about 10 minutes, or until the salmon separates easily with a fork and the Panko is toasted golden brown.