Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Peel the sweet potato and cut it into small 1/2-inch cubes to ensure they roast quickly and evenly.
Place the sweet potato cubes and broccoli florets on the baking sheet, drizzle with olive oil, and sprinkle with half of the salt, pepper, and garlic powder.
Toss the vegetables to coat thoroughly and spread them out in a single layer; roast for 10 minutes.
While vegetables roast, pat the salmon fillet dry and season the top with the remaining salt, pepper, garlic powder, and the dried oregano.
Remove the baking sheet from the oven, slide the vegetables to the sides, and place the salmon fillet in the center.
Return the pan to the oven and roast for an additional 12-15 minutes, or until the salmon is opaque and flakes easily with a fork.
Squeeze the fresh lemon juice over the entire tray before serving to brighten the flavors.