Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Peel the sweet potato and dice it into uniform 1/2-inch cubes for even cooking.
In a bowl, toss the sweet potato cubes 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 15 minutes.
While the potatoes roast, trim the woody ends off the asparagus spears.
Remove the baking sheet, add the asparagus, and toss with the potatoes; roast for another 10 minutes until the vegetables are tender.
Pat the cod fillet dry with a paper towel 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 skillet over medium-high heat.
Place the cod in the skillet and sear for 3-4 minutes per side until the fish is opaque and flakes easily with a fork.
Drizzle the fresh lemon juice over the cod and serve immediately alongside the roasted vegetables.