1. Preheat oven to 425 degree.
2. Line a large rimmed baking sheet with parchment paper, and keep it aside.
3. For sauce, in a bowl combine maple syrup, canola oil, garlic, lemon juice, and Dijon mustard. Whisk well. Reserve ½ cup of sauce and set it aside.
4. Throw Brussels sprouts, and onion into the sauce. Toss and coat evenly.
5. Sprinkle salt and pepper. Mix.
6. On the baking sheet, spread the vegetables evenly to roast and caramelize well.
7. Place it in the middle rack of the oven and roast for about 20 minutes. Stir once half way through.
8. Once the Brussels are caramelized, remove the sheet from oven. Turn oven to broil.
9. Sprinkle raisins over the top. Set salmon fillets on it.
10. Brush fillets with remaining maple sauce. Coat evenly.
11. Place tray back in oven, and broil for about 7 minutes or until slightly golden on top and flakes easily with fork.
12. Serve roasted maple salmon hot with parsley garnish.