Preheat oven or grill to 400 degrees. Pat the salmon with paper towels and place on a parchment-lined baking sheet. Season with salt and pepper. Bake for 20-25 minutes (grill time will be slightly less), until fish flakes with a fork. Remove the salmon onto a cutting board and use a fork to make flaky pieces.

Bring a large pot of water to a boil. Cook the pasta 8-9 minutes until al dente. Drain and rinse with cool water.

In a large bowl, combine mayonnaise, onion, celery, mustard and dill. Add the pasta and toss together. Gently fold in the flaked salmon. Chill before serving.