Step 1

Heat the oven to 425°F. Arrange a rack in the middle of the oven and heat to 425°F. Place the frozen salmon fillets skin-side down in an 8x8-inch baking dish.

Step 2

Combine the mustard, maple syrup, garlic, and salt in a small bowl. Place the mustard, maple syrup, garlic, red pepper flakes if using, and salt in a small bowl and stir to combine.

Step 3

Brush the salmon with the mustard mixture. Brush or spoon all of the mustard mixture evenly over the salmon.

Step 4

Cover the baking dish and bake for 15 minutes. Cover the baking dish tightly with aluminum foil. Roast for 15 minutes, until a knife can pierce the salmon completely with only slight, icy resistance.

Step 5

Uncover and roast for another 8 to 10 minutes. Carefully remove the foil. Continue roasting until the salmon can be easily flaked with a fork or a probe thermometer inserted in the thickest part of the salmon registers 145°F, 8 to 10 minutes more. Wild salmon tends to cook faster than farm-rasied salmon, so begin checking salmon at 8 minutes. The flesh should appear moist, but not raw or translucent.

Step 6

Rest and serve. Remove the salmon from the oven and let rest uncovered for 3 minutes. Serve with a hearty salad or quick pasta side.