Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper for easy cleanup.
Arrange the salmon fillet and the trimmed asparagus spears on the prepared baking sheet in a single layer.
Drizzle the olive oil over the asparagus and toss gently to coat, then sprinkle with a pinch of the sea salt and black pepper.
In a small mixing bowl, combine the almond flour, garlic powder, and dried parsley until well blended.
Spread the Dijon mustard evenly over the top of the salmon fillet to act as a binder for the crust.
Carefully press the almond flour mixture onto the mustard-coated salmon to create an even, golden layer.
Season the salmon with the remaining sea salt and black pepper.
Roast in the center of the oven for 12 to 15 minutes, or until the salmon flakes easily with a fork and the asparagus is tender-crisp.
Remove from the oven and serve immediately with a fresh lemon slice for a bright finish.