Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Trim the woody ends off the asparagus spears and place them 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, lemon juice, minced garlic, dried oregano, sea salt, and black pepper.
Drizzle the herb and lemon mixture over both the salmon and the asparagus, using a brush or your hands to ensure the asparagus is evenly coated.
Place the fresh lemon slice on top of the salmon fillet to infuse it with bright citrus flavor during cooking.
Bake in the center of the oven for 12 to 15 minutes, or until the salmon is opaque and flakes easily with a fork and the asparagus is tender-crisp.
Remove from the oven and serve immediately while hot.