Make Glaze: Combine brown sugar, soy sauce, olive oil, lemon juice, garlic, Dijon mustard, black pepper, and red pepper flakes in a bowl.
Marinate: Pour glaze over salmon fillets and refrigerate for 30 minutes.
Preheat Oven: Preheat oven to 375°F.
Bake: Place salmon fillets on a parchment-lined baking sheet, skin side down. Bake for 15-20 minutes or until cooked through.
Serve: Garnish with parsley or green onions.
