Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
Snap off the woody ends of the asparagus and toss the spears on the baking sheet with olive oil, a pinch of sea salt, and black pepper.
Roast the asparagus for 12-15 minutes until the tips are slightly charred and the stalks are tender.
While the vegetables roast, pat the sirloin steak completely dry with paper towels and season both sides generously with the remaining salt and pepper.
Heat a heavy cast-iron skillet over medium-high heat until it begins to smoke slightly, then carefully place the steak in the pan.
Sear the steak for 3-4 minutes per side to achieve a deep golden-brown crust and a medium-rare internal temperature.
Reduce the heat to medium and add the ghee and smashed garlic cloves, tilting the pan to spoon the bubbling garlic butter over the steak for 60 seconds.
Transfer the steak to a cutting board to rest for 5 minutes before slicing it into thin strips against the grain.
Finish the roasted asparagus with a squeeze of fresh lemon juice and serve immediately alongside the warm, garlic-basted steak.