Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Cut the sweet potato into 1/2-inch thick wedges and trim the ends off the green beans.
Place the potatoes and beans on the sheet, drizzle with olive oil, and season with half of the salt and pepper.
Roast the vegetables for 20 to 25 minutes, flipping the potatoes halfway through, until the edges are golden and caramelized.
While vegetables roast, pat the cod fillets dry with a paper towel and season both sides with garlic powder and the remaining salt and pepper.
Heat the ghee in a non-stick skillet over medium-high heat until shimmering.
Carefully place the cod in the pan and sear for 3 to 4 minutes per side until the exterior is golden and the fish flakes easily.
In a small bowl, whisk together the Greek yogurt, lemon juice, and fresh chopped dill to create the sauce.
Plate the pan-seared cod alongside the roasted vegetables and spoon the bright lemon-dill sauce over the fish.