Preheat oven to 400°F and line a sheet pan with foil or parchment paper.
Arrange asparagus in a single layer on one side of the pan and drizzle with 1 tablespoon melted butter, salt, and pepper.
Place salmon fillets on the other side of the pan and season with salt, pepper, and dill.
Mix remaining melted butter with minced garlic and half the lemon juice, then brush over salmon fillets.
Top salmon with lemon slices and bake for 12-15 minutes until salmon flakes easily with a fork.
Drizzle remaining fresh lemon juice over everything and garnish with fresh parsley before serving.