Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper for easy cleanup.
Trim the woody ends off the asparagus spears and place them on one side of the baking sheet.
Drizzle the asparagus with olive oil and season with a pinch of sea salt and black pepper, tossing to coat evenly.
Pat the salmon fillet dry with a paper towel and place it on the other side of the baking sheet.
In a small bowl, combine the Dijon mustard, finely chopped parsley, chopped dill, garlic powder, and lemon juice to form a paste.
Spread the herb paste evenly over the top of the salmon fillet, pressing gently so it adheres to the surface.
Bake for 12 to 15 minutes, or until the salmon is opaque and flakes easily with a fork and the asparagus is tender.
Remove from the oven and serve immediately, garnishing with an extra wedge of lemon if desired.