Preheat your oven to 400°F (200°C).
Dice the russet potato into 1/2-inch cubes and toss with half of the olive oil, sea salt, and black pepper.
Spread the potatoes in a single layer on a parchment-lined baking sheet and roast for 20-25 minutes until golden and crispy.
While the potatoes roast, season the sirloin steak on both sides with the remaining salt and pepper.
Heat a cast-iron skillet over medium-high heat with the remaining olive oil.
Sear the steak for 3-4 minutes per side for medium-rare, adding the minced garlic and fresh rosemary to the pan in the final minute of cooking.
Remove the steak from the skillet and let it rest on a cutting board for 5 minutes before slicing against the grain.
Steam the broccoli florets in a small amount of water for 3-4 minutes until they are tender-crisp and bright green.
Assemble your power bowl by layering the roasted potatoes and steamed broccoli, then topping with the sliced steak and any remaining pan juices.