Pat the cod fillets dry with a paper towel and season both sides evenly with the sea salt and black pepper.
In a small mixing bowl, whisk together the Greek yogurt, chopped fresh dill, lemon juice, lemon zest, and minced garlic until the sauce is creamy and well combined.
Heat the olive oil in a large non-stick skillet over medium-high heat until it begins to shimmer.
Carefully place the cod fillets in the skillet and sear for 3 to 4 minutes on the first side without moving them, allowing a golden crust to form.
Flip the fillets gently and cook for another 3 to 4 minutes until the fish is opaque and flakes easily with a fork.
While the fish is finishing, steam the asparagus spears for 4 to 5 minutes until they reach a vibrant green, crisp-tender texture.
Plate the pan-seared cod over a bed of warm cooked quinoa, top with a generous dollop of the lemon-dill sauce, and serve with the steamed asparagus on the side.