For best results, allow the salmon to come to room temperature before preparing the recipe (about 20 minutes).
Place a large sheet of aluminum foil on a baking sheet and brush it with olive oil. Pat each piece of salmon dry and place it on the foil skin side down. Sprinkle the salmon with the kosher salt evenly divided among the fillets.
In a medium bowl, mix together the light brown sugar, Dijon mustard, olive oil, water, onion powder, and garlic powder. Use a pastry brush to apply the glaze on the top of the salmon. Add a few grinds of fresh ground black pepper.
Broil (on a center rack if possible) for about 8 to 11 minutes for 1-inch thick salmon, until it’s just tender and pink at the center (the internal temperature should be between 125 to 130°F in the center). Broil about 5 minutes for very thin salmon. Keep an eye on it because it can brown quickly. Serve immediately.