Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Peel and cube the sweet potato into half-inch pieces, then toss them on the baking sheet with 0.5 tablespoons of avocado oil and a pinch of sea salt.
Roast the sweet potatoes for 20-25 minutes, tossing halfway through, until they are golden brown and crispy on the edges.
While the potatoes roast, pat the sirloin steak dry with a paper towel and season both sides evenly with the remaining sea salt, black pepper, and garlic powder.
Heat the remaining 0.5 tablespoons of avocado oil in a cast-iron skillet over medium-high heat until the oil is shimmering and just starting to smoke.
Place the steak in the hot skillet and sear for 3-4 minutes per side for medium-rare, or until it reaches your desired level of doneness.
Remove the steak from the pan and let it rest on a cutting board for at least 5 minutes to lock in the juices.
In the same skillet, add the asparagus spears and sauté in the remaining pan drippings for 3-5 minutes until they are bright green and tender-crisp.
Slice the rested steak against the grain and serve immediately alongside the crispy sweet potatoes and sautéed asparagus.