Preheat your oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Wash the asparagus and trim away the tough, woody ends, then place the spears on one side of the prepared baking sheet.
Drizzle the asparagus with olive oil and season with half of the sea salt and black pepper, tossing to coat evenly.
In a small mixing bowl, combine the Dijon mustard, minced garlic, lemon zest, finely chopped parsley, and finely chopped dill to create a paste.
Place the salmon fillet on the other side of the baking sheet and season with the remaining sea salt and pepper.
Spread the herb-mustard mixture evenly over the top of the salmon fillet, pressing it down slightly to adhere.
Bake for 12-15 minutes, or until the salmon is opaque and flakes easily with a fork and the asparagus is tender and lightly charred.