Preheat your oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Trim the woody ends off the asparagus spears and place them on one side of the prepared baking sheet.
Pat the cod fillets dry with a paper towel and place them on the other side of the baking sheet.
In a small bowl, whisk together the olive oil, the juice of half the lemon, minced garlic, dried oregano, sea salt, and black pepper.
Drizzle the herb oil mixture evenly over both the cod fillets and the asparagus spears, tossing the asparagus slightly to coat.
Slice the remaining half of the lemon into thin rounds and place them on top of the cod fillets.
Bake in the center of the oven for 12 to 15 minutes, or until the cod is opaque and flakes easily with a fork and the asparagus is tender.
Serve the baked cod and asparagus over the warm cooked quinoa, garnished with a sprinkle of fresh chopped parsley.