Place the sugar, soy sauce, hoisin sauce, ginger, dash of red pepper flakes, garlic, and lime juice in a medium nonreactive saucepan.
Bring the mixture to a boil, reduce the heat to medium, and cook for 15 to 20 minutes, or until the sauce forms a glaze. Set aside.
Preheat the broiler.
Place the salmon fillets on a broiler pan and baste with the sauce. Let sit for 15 minutes. Broil them until cooked through, about 8 minutes, basting again with the glaze.
Remove the salmon from the heat and baste once more with the glaze before serving.