Preheat your oven to 400°F (200°C).
Dice the Russet potato into half-inch cubes to ensure even roasting and maximum crispiness.
In a bowl, toss the potato cubes with 0.25 tablespoons of avocado oil, the dried rosemary, dried thyme, and half of the sea salt and black pepper.
Spread the potatoes in a single layer on a parchment-lined baking sheet and roast for 20 minutes.
While potatoes roast, season the sirloin steak on both sides with the remaining sea salt and black pepper.
Heat the remaining 0.25 tablespoons of avocado oil in a cast-iron skillet over medium-high heat until shimmering.
Sear the steak for 4-5 minutes per side for medium-rare, or until it reaches your preferred level of doneness.
During the last minute of searing, add the minced garlic to the skillet, spooning the garlic-infused oil over the steak.
Add the asparagus spears to the baking sheet with the potatoes for the final 8 minutes of roasting time.
Remove the steak from the skillet and let it rest for 5 minutes before slicing against the grain and serving alongside the roasted vegetables.