Preheat your oven to 400°F and line a baking sheet with parchment paper.
Toss the cubed sweet potatoes with 0.5 tbsp of olive oil, 0.25 tsp of sea salt, and the garlic powder.
Spread the sweet potatoes on the baking sheet and roast for 20-25 minutes until tender and caramelized on the edges.
While potatoes roast, bring a pot of water to a boil and cook the ear of corn for 5-7 minutes until bright yellow, then drain.
Pat the cod fillets very dry with paper towels and season both sides with the remaining sea salt, black pepper, and dried oregano.
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 skillet and sear for 3-4 minutes per side until the exterior is golden and the fish flakes easily with a fork.
Serve the pan-seared cod immediately with a fresh lemon slice, the roasted sweet potatoes, and the boiled corn.