Preheat & Prepare Pan: Preheat your oven to 400°F (200°C). Line a large rimmed baking sheet with parchment paper or heavy-duty foil for effortless cleanup.
Whisk the Garlic Herb Glaze: In a small glass bowl, whisk together melted butter, olive oil, minced garlic, 1 tablespoon fresh lemon juice, chopped dill, chopped parsley, sea salt, black pepper, and smoked paprika.
Arrange on Sheet Pan: Place the salmon fillets skin-side down in the center of the baking sheet, leaving about 2 inches of space between them. Arrange the trimmed asparagus spears on both sides in a single layer. Tuck sliced lemon rounds between the fillets.
Glaze Generously: Brush approximately two-thirds of the garlic herb butter mixture over the tops and sides of the salmon fillets. Drizzle the remaining butter over the asparagus and toss the spears lightly to coat.
Roast to Tender Perfection: Bake in the preheated oven for 12 to 14 minutes, until the salmon flakes gently with a fork and reaches an internal temperature of 125°F to 130°F (52°C-54°C) for succulent medium doneness.
Broil & Garnish: For a golden sizzle, broil on HIGH for the final 60 seconds (watch closely). Spoon any warm garlic butter pan juices over the salmon, scatter with fresh dill, and serve immediately with lemon wedges!