Pat the cod fillets dry with paper towels to ensure a proper sear, then season both sides evenly with sea salt, black pepper, and garlic powder.
In a small mixing bowl, whisk together the Greek yogurt, finely chopped fresh dill, lemon juice, and Dijon mustard until the sauce is smooth and creamy.
Heat the extra virgin olive oil in a large non-stick skillet over medium-high heat until shimmering.
Carefully place the cod fillets in the skillet and sear for 3 to 4 minutes per side, or until the exterior is golden brown and the fish flakes easily with a fork.
While the fish cooks, steam or lightly sauté the asparagus spears until they are bright green and tender-crisp.
Arrange the warm cooked quinoa on a plate, top with the pan-seared cod, and drizzle the lemon-dill sauce generously over the fish.
Serve immediately with the steamed asparagus on the side for a complete, clean-eating meal.