Line a broiler pan rack with foil. Spray the foil with cooking spray. Preheat the broiler.
To make the glaze, whisk together the brown sugar, ginger, mustard and soy sauce in a small bowl. Place the salmon on the broiler pan rack and spoon the glaze over the top. Broil, 6 inches from the heat, until the salmon is lightly browned and just opaque in the center, 4 to 5 minutes. Do not turn.