Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Place the cod fillets and the trimmed asparagus spears onto the prepared baking sheet.
Drizzle the olive oil over the asparagus and toss lightly to ensure even coating.
Season the cod fillets evenly with the lemon zest, garlic powder, 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 tender-crisp.
While the fish bakes, gently warm the pre-cooked quinoa in a small saucepan or microwave until steaming.
Remove the tray from the oven, drizzle the fresh lemon juice over the fish and vegetables, and garnish with chopped parsley.
Serve the baked cod and roasted asparagus immediately over the warm bed of quinoa.