Preheat oven to 400ºF. Coat a shallow baking dish with cooking spray.
Season both sides of salmon with salt and pepper; place salmon in prepared baking dish.
In a small bowl, whisk together Dijon mustard, honey, water, vinegar, dry mustard and garlic powder. Remove 2 tablespoons of mustard sauce and brush over salmon fillets. Stir dill into remaining mustard sauce and set aside.
Roast until salmon is fork-tender, about 15 minutes. Serve salmon with reserved mustard sauce spooned over top.
*Yields about 4 to 5 ounces of salmon and 1 1/2 tablespoons of sauce per serving.