Remove the rump steak from the refrigerator 20 minutes before cooking to reach room temperature.
Pat the steak thoroughly dry with paper towels and season both sides with sea salt and black pepper.
Heat a heavy cast-iron skillet over medium-high heat until very hot, then place the steak in the dry pan.
Sear the steak for 3 to 4 minutes per side for medium-rare, or until a golden-brown crust forms.
Reduce heat to medium and add the ghee, smashed garlic clove, and fresh rosemary to the pan.
Tilt the pan and spoon the melting garlic-infused ghee over the steak repeatedly for 1 minute.
Remove the steak from the pan and let it rest on a cutting board for 5 minutes.
While the steak rests, toss the asparagus into the same skillet and sauté in the remaining juices for 3 minutes until vibrant and tender.
Slice the steak against the grain and serve alongside the buttery asparagus.