Preheat your oven to 400°F and line a rimmed baking sheet with parchment paper.
Peel the sweet potato and cut into 1/2-inch cubes, then toss with half of the avocado oil and a pinch of sea salt.
Spread the sweet potatoes in a single layer on the baking sheet and roast for 20-25 minutes until tender and caramelized.
While potatoes roast, pat the steak completely dry with paper towels and season both sides generously with sea salt and black pepper.
Heat the remaining avocado oil in a cast-iron skillet over medium-high heat until it begins to shimmer.
Place the steak in the hot skillet and sear for 3-4 minutes without moving it to develop a deep golden crust.
Flip the steak and add the ghee, minced garlic, and chopped rosemary to the pan.
Tilt the pan slightly and use a spoon to continuously baste the steak with the melting garlic herb butter for another 3 minutes.
Remove the steak from the pan and let it rest on a cutting board for at least 5 minutes to lock in the juices.
Briefly sauté or steam the asparagus spears until they are bright green and tender-crisp.
Slice the steak against the grain and serve alongside the roasted sweet potatoes and asparagus, drizzling any remaining pan juices over the meat.