Preheat your oven to 400°F and line a large baking sheet with parchment paper.
In a small mixing bowl, whisk together the extra virgin olive oil, fresh lemon juice, lemon zest, minced garlic, and dried oregano.
Place the cod fillet on one side of the baking sheet and the trimmed asparagus spears on the other side.
Drizzle the lemon-herb marinade over both the fish and the asparagus, using a brush or clean hands to ensure the asparagus is evenly coated.
Season the entire sheet pan with sea salt and black pepper.
Bake in the center rack for 12 to 15 minutes, or until the cod is opaque and flakes easily with a fork and the asparagus is vibrant and tender.
While the fish bakes, warm your pre-cooked quinoa in a small saucepan or microwave.
Plate the cod and asparagus over the bed of fluffy quinoa and garnish with freshly chopped parsley before serving.