Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper for easy cleanup.
In a small saucepan, combine the quinoa with 0.5 cups of water; bring to a boil, then reduce heat to low, cover, and simmer for 15 minutes until the water is absorbed and the grain is fluffy.
Place the cod fillets and the trimmed asparagus spears onto the prepared baking sheet, ensuring they are in a single layer.
In a small bowl, whisk together the olive oil, lemon juice, minced garlic, chopped parsley, dill, sea salt, and black pepper.
Drizzle the lemon-herb sauce evenly over the cod fillets and the asparagus, using a pastry brush to coat the fish thoroughly.
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 crisp-tender.
Divide the cooked quinoa between plates and top with the roasted cod and asparagus, drizzling any remaining juices from the pan over the top before serving.