Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper.
Peel and cube the sweet potato into 1/2-inch pieces, then toss them on the baking sheet with half of the olive oil, garlic powder, and a pinch of salt and pepper.
Roast the sweet potatoes for 15 minutes.
Remove the tray from the oven, add the broccolini to the other side, drizzle with the remaining olive oil, and return to the oven for 10-12 minutes until tender.
While the vegetables roast, pat the steak dry with a paper towel and season both sides generously with the remaining salt and pepper.
Heat a heavy cast-iron skillet over medium-high heat until very hot.
Place the steak in the dry skillet and sear for 3-4 minutes per side for medium-rare, or until your desired doneness is reached.
During the last minute of searing, add the ghee to the pan and spoon the melted fat over the steak to baste it.
Transfer the steak to a cutting board and let it rest for 5 minutes before slicing against the grain.
Plate the sliced steak alongside the roasted sweet potatoes and charred broccolini.