Preheat your oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Pat the cod fillets thoroughly dry with paper towels to ensure they bake with a firm, flaky texture rather than steaming.
In a small glass bowl, whisk together the olive oil, fresh lemon juice, lemon zest, minced garlic, and dried oregano until well combined.
Place the cod fillets and the trimmed asparagus spears onto the prepared baking sheet in a single layer.
Drizzle the lemon-herb mixture evenly over both the fish and the asparagus, then season everything with the sea salt and black pepper.
Bake for 12 to 15 minutes until the cod is opaque and flakes easily with a fork and the asparagus is crisp-tender.
Transfer the cooked quinoa to a plate, top with the baked cod and asparagus, and garnish with a sprinkle of fresh chopped parsley before serving.