Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Peel the sweet potato and cut it into uniform 1/2-inch cubes for even roasting.
Toss the sweet potato cubes on the baking sheet with 0.25 tablespoons of olive oil and a pinch of sea salt and black pepper.
Roast the sweet potatoes for 20-25 minutes, tossing halfway through, until they are tender and the edges are golden brown.
While the potatoes roast, season both sides of the top sirloin steak with garlic powder and the remaining sea salt and black pepper.
Heat a cast-iron skillet over medium-high heat with the remaining 0.25 tablespoons of olive oil until shimmering.
Place the steak in the hot skillet and sear for 4-5 minutes per side for medium-rare, or until it reaches your preferred level of doneness.
Remove the steak from the skillet and let it rest on a cutting board for at least 5 minutes to lock in the juices.
In the same skillet used for the steak, add the kale and balsamic vinegar, sautéing for 2-3 minutes until the leaves are bright green and wilted.
Slice the rested steak against the grain and assemble your bowl with the sautéed kale, roasted sweet potatoes, and beef.