Preheat your oven to 400°F (200°C).
Peel and cube the sweet potato into 1-inch pieces, then toss with half of the avocado oil and a pinch of sea salt on a parchment-lined baking sheet.
Roast the sweet potatoes for 20-25 minutes, flipping halfway through, until they are tender and slightly caramelized.
In a small bowl, mix the ground coffee with a pinch of salt and black pepper to create the dry rub.
Pat the sirloin steak dry with a paper towel and coat both sides evenly with the coffee rub, pressing it into the meat.
Heat the remaining avocado oil in a cast-iron skillet over medium-high heat 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 desired level of doneness.
Remove the steak from the pan and let it rest on a cutting board for at least 5 minutes to keep it juicy.
While the steak rests, add the green beans and minced garlic to the same skillet, sautéing for 5-7 minutes until they are tender-crisp and bright green.
Slice the rested steak against the grain and serve it alongside the roasted sweet potatoes and garlic green beans.