Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Wash the asparagus and trim away the woody bottom ends, then place the spears on one side of the prepared baking sheet.
Place the salmon fillet on the other side of the baking sheet, ensuring there is space between the fish and the vegetables.
In a small bowl, whisk together the extra virgin olive oil, minced garlic, dried oregano, sea salt, and black pepper.
Drizzle the herb and oil mixture over both the salmon and the asparagus, using your hands or a brush to coat them evenly.
Slice the half lemon into thin rounds and layer them directly on top of the salmon fillet.
Bake in the center of the oven for 12 to 15 minutes, or until the salmon reaches an internal temperature of 145°F and flakes easily with a fork.
Remove from the oven and garnish immediately with freshly chopped parsley before serving warm.