- Preheat oven to 220°C (425°F).
- In a large bowl, whisk together the maple syrup, oil, lemon juice, mustard, salt, and pepper. Pour 60 mL (¼ cup) of the maple sauce into a small bowl and set aside.
- Line a baking sheet with parchment paper or foil wrap. Place Brussel sprouts and onion in the large bowl containing the maple sauce and stir gently to coat. Transfer vegetables to baking sheet and bake on oven's middle rack, stirring once at midway point, until tender and golden brown, about 20 minutes.
- Remove baking sheet from oven and preheat broiler. Sprinkle vegetables with raisins, place salmon on top, and brush with maple sauce in the small bowl. Return baking sheet to oven and grill salmon until lightly browned and until it flakes easily with a fork, about 7 minutes. Sprinkle with parsley before serving.
Give your vegetables ample space on the baking sheet to ensure even roasting rather than steaming.