Pat the sirloin steak completely dry with paper towels to ensure a proper sear, then season both sides evenly with sea salt and black pepper.
Heat a cast-iron skillet over medium-high heat and add the avocado oil, swirling to coat the bottom of the pan.
Once the oil is shimmering, carefully place the steak in the skillet and sear undisturbed for 3 to 4 minutes until a deep golden-brown crust has formed.
Flip the steak and immediately add the ghee, smashed garlic cloves, rosemary, and thyme to the skillet.
Tilt the pan slightly so the melting ghee pools with the herbs and garlic, then use a large spoon to continuously baste the top of the steak for 2 to 3 minutes.
Add the asparagus spears to the empty side of the skillet during the final 4 minutes of cooking, tossing them in the herb-infused ghee until tender-crisp.
Transfer the steak to a cutting board and let it rest for at least 5 minutes to allow the juices to redistribute before slicing against the grain.