Preheat your oven to 400°F and set a grill pan over medium-high heat on the stove.
In a small bowl, whisk together the olive oil, lemon juice, lemon zest, minced garlic, dried oregano, sea salt, and black pepper to create the marinade.
Place the asparagus spears on a parchment-lined baking sheet and drizzle with half of the lemon-garlic marinade, tossing to coat evenly.
Roast the asparagus in the oven for 12 to 15 minutes until they are tender and slightly charred at the tips.
While the asparagus roasts, brush the remaining marinade onto the cod fillets and place them on the hot grill pan.
Grill the fish for 4 to 5 minutes per side, or until the flesh is opaque and flakes easily with a fork.
Warm the cooked quinoa and divide it between plates, topping with the grilled fish and serving the roasted asparagus alongside.