Preheat your oven to 425°F for roasting the potatoes.
Wash the baby potatoes and cut them into halves or quarters for even roasting. Toss them in a bowl with olive oil, a pinch of salt, and black pepper.
Spread the potatoes evenly on a baking sheet and roast for 20-25 minutes, stirring halfway, until they are crispy on the outside and tender inside.
While the potatoes roast, season the lean sirloin steak with salt and pepper on both sides.
Mince the garlic cloves. Heat a skillet over medium-high heat and add a small amount of olive oil.
Place the steak in the hot skillet and sear for about 3-4 minutes on each side for medium-rare, adjusting the time as needed for your desired doneness.
In the last minute of cooking, add the minced garlic and unsalted butter to the pan. Spoon the melted garlic butter over the steak to enhance the flavor.
Meanwhile, blanch the green beans in boiling water for 2-3 minutes until they are tender yet crisp, then quickly drain.
Plate the steak, roasted potatoes, and green beans together. Drizzle any remaining garlic butter from the pan over the steak and serve immediately.