Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Peel the sweet potato and cut it into 1/2-inch cubes. Toss them on the baking sheet with 0.5 tbsp of olive oil, 0.25 tsp garlic powder, and a pinch of salt and pepper.
Roast the sweet potatoes for 15 minutes. While they roast, trim the woody ends off the asparagus spears.
Remove the tray from the oven, add the asparagus to the other side of the sheet, and roast for an additional 8-10 minutes until the potatoes are caramelized and asparagus is tender-crisp.
Pat the cod fillets dry with paper towels. In a small bowl, mix the turmeric, remaining garlic powder, salt, and pepper, then rub the mixture evenly over both sides of the fish.
Heat the remaining 0.5 tbsp of olive oil in a non-stick or cast-iron skillet over medium-high heat.
Place the cod in the hot pan and sear for 3-4 minutes per side, or until the fish is opaque throughout and flakes easily with a fork.
Plate the golden cod alongside the roasted vegetables and finish with a bright squeeze of fresh lemon juice over the entire dish.