Preheat your oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Trim the tough, woody ends off the asparagus spears and place the spears on the prepared baking sheet.
Mince the garlic cloves finely.
Drizzle half of the olive oil over the asparagus and toss with the minced garlic, dried thyme, and a pinch of salt and pepper.
Spread the asparagus in a single layer and roast for 12 to 15 minutes until tender and slightly charred.
While the asparagus roasts, season the sirloin steak on both sides with the remaining salt and pepper.
Heat the remaining olive oil in a cast-iron skillet over medium-high heat until shimmering.
Sear the steak for 4 to 5 minutes per side for medium-rare, or until it reaches your desired doneness.
Remove the steak from the pan and let it rest on a cutting board for 5 minutes to lock in the juices.
Plate the sliced steak alongside the roasted asparagus and finish with a bright squeeze of fresh lemon juice.