Preheat your oven to 400°F and line a large sheet pan with parchment paper for easy cleanup.
Trim the woody, fibrous ends off the asparagus spears and place them on one side of the prepared baking sheet.
Pat the cod fillets completely dry with a paper towel and arrange them on the other side of the pan.
In a small bowl, whisk together the extra virgin olive oil, minced garlic, dried oregano, sea salt, and black pepper.
Drizzle the herb oil mixture over both the cod and the asparagus, using your hands or a brush to ensure the asparagus is evenly coated.
Thinly slice the lemon half into rounds and place them directly on top of the cod fillets to infuse them with brightness.
Roast in the center of the oven for 12-15 minutes, or until the cod is opaque and flakes easily with a fork and the asparagus is tender.
Transfer the baked cod and asparagus to a plate over a bed of warm cooked quinoa and serve immediately.