Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Halve the fingerling potatoes and toss them in a bowl with the olive oil, half the sea salt, and half the black pepper.
Spread the potatoes in a single layer on the baking sheet and roast for 15 minutes.
Trim the woody ends from the asparagus and add the spears to the baking sheet with the potatoes, roasting for an additional 10 minutes until the vegetables are tender and browned.
While the vegetables roast, pat the steak dry with a paper towel and season both sides with the remaining salt and pepper.
Heat a cast-iron skillet over medium-high heat and add the ghee.
Place the steak in the hot skillet and sear for 3 to 4 minutes per side for medium-rare.
During the last 2 minutes of cooking, add the smashed garlic cloves and chopped rosemary to the pan, spooning the melted herb ghee over the steak repeatedly.
Remove the steak from the pan and let it rest for 5 minutes before slicing and serving alongside the roasted potatoes and asparagus.