Preheat the oven's broiler to HI heat and set the oven rack about 6-8 inches from the heat source. Lightly spray a rimmed baking sheet with cooking spray.
Place the salmon on a prepared baking sheet and arrange the asparagus around the salmon. Pour lemon juice over salmon and asparagus. Lightly drizzle olive oil over the top of the salmon and asparagus. Sprinkle the garlic, parsley, and zest evenly over the top of the salmon and asparagus. Season all with salt and pepper. Arrange lemon slices over the top.
Broil for 8-10 minutes, or until salmon is cooked to your desired preference.
If desired, garnish with additional fresh parsley.