Lower oven rack to middle lower position and preheat oven to 450 degrees. Spray heavy duty baking sheet with nonstick cooking spray.

In a large bowl, toss potatoes with 2 tablespoons of olive oil, 1/2 teaspoon of kosher salt, 1/4 teaspoon of freshly ground pepper and 1/8 teaspoon garlic powder. Transfer to baking sheet and arrange on either side of baking sheet, cut side down. Roast in oven for 10 minutes.

While potatoes are roasting, combine asparagus with 1 tablespoon of olive oil, 1/2 teaspoon of kosher salt. 1/4 teaspoon of freshly ground pepper and 1/8 teaspoon garlic powder. 

Season salmon all over with kosher salt and freshly ground pepper, then brush all sides with hoisin sauce. 

Remove sheet pan from oven after 10 minutes and add asparagus to center of sheet pan. Arrange salmon portions, not touching, over asparagus. 

Roast for another 10-15 minutes depending on thickness of salmon portions and size of asparagus. 

While salmon is cooking, combine butter, parsley and garlic. When salmon is done cooking, remove sheet pan and top each salmon portion with 1/2 tablespoon of garlic herb butter then top with a squeeze of fresh lemon juice.

Top potatoes and asparagus with remaining two tablespoon of garlic herb butter and serve.