Preheat the oven to 375°F.
Coat one side of each salmon fillet with the mustard and season with salt and pepper.
Sprinkle each fillet with 1 tablespoon of bread crumbs, patting them down into the mustard to make a crust, and put them in a cast-iron skillet.
Place the skillet into the oven and bake for 12 to 15 minutes, or until the salmon is just cooked and the crust is golden. Serve immediately.