Preheat the oven to 425°F (220°C) and line a rimmed baking sheet with parchment paper.
In a large mixing bowl, combine the broccoli, bell peppers, and red onion.
Drizzle vegetables with 2 tablespoons of olive oil and season with half of the garlic powder, paprika, oregano, salt, and pepper. Toss to coat evenly.
Spread the seasoned vegetables in a single layer across the prepared sheet pan.
Roast the vegetables in the oven for 8 minutes.
While vegetables roast, toss the steak cubes in the same mixing bowl with the remaining 1 tablespoon of olive oil and the remaining spices.
Remove the sheet pan from the oven and move the vegetables to the edges to create space in the center.
Place the steak cubes in the center of the pan in a single layer.
Switch the oven to the high broil setting and return the pan to the upper rack.
Broil for 4 to 6 minutes or until the steak is browned and reaches an internal temperature of 135°F for medium-rare.
Allow the steak to rest on the pan for 5 minutes before serving or portioning into meal prep containers.