Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Slice the red bell pepper into thin strips and cut the zucchini into half-moon shapes.
In a large bowl, toss the broccoli florets, bell pepper strips, and zucchini with half of the olive oil, the garlic powder, and half of the sea salt and black pepper.
Spread the seasoned vegetables in a single layer on the prepared baking sheet and roast for 18 to 20 minutes until tender and slightly charred.
Pat the top sirloin steak dry with paper towels and season both sides with the remaining sea salt and black pepper.
Heat a cast-iron skillet over medium-high heat and add the remaining olive oil.
Place the steak in the hot skillet and sear for 3 to 4 minutes per side until a golden-brown crust forms and it reaches your desired level of doneness.
Transfer the steak to a cutting board and let it rest for at least 5 minutes to keep the juices locked in.
Finely chop the fresh rosemary leaves while the steak rests.
Slice the rested steak against the grain into thin strips.
Arrange the roasted vegetables in a bowl, top with the sliced steak, and sprinkle with fresh rosemary before serving.