preheat the oven to 425 degrees.

line a sheet pan with parchment paper.

place the fish fillets skin side down on the sheet pan.

sprinkle generously with salt and pepper.

combine the sour cream, 2 mustards, shallots, 1 teaspoon salt, and 1/2 teaspoon pepper in a small bowl.

spoon the sauce evenly over the fish fillets, making sure the fish is completely covered.

bake for 10 to 15 minutes, depending on the thickness of the fish, until it's barely done.

be sure not to overcook it!

serve with the sauce from the pan spooned over the top.