Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
Pat the cod fillets dry with a paper towel to ensure the best texture and place them on one side of the prepared baking sheet.
Trim the woody ends off the asparagus spears and arrange them in a single layer on the other side of the baking sheet.
In a small bowl, whisk together the olive oil, lemon juice, lemon zest, minced garlic, and dried oregano until well combined.
Brush the lemon-herb mixture generously over the cod fillets and drizzle the remaining sauce over the asparagus spears.
Season both the fish and the vegetables evenly with the sea salt and black pepper.
Bake for 12 to 15 minutes, or until the cod is opaque and flakes easily with a fork and the asparagus is tender.
Transfer the warm cooked quinoa to a plate, top with the roasted cod and asparagus, and garnish with freshly chopped parsley before serving.