Heat a large skillet, preferably cast iron, over medium-high, 3 minutes. Pour in 1 Tbsp. oil, add lamb, and use a heatproof rubber spatula or a wooden spoon to smash down, spread out, and flatten meat onto pan’s surface. You’re making a big flat lamb patty at this point. Season surface evenly with kosher salt and black pepper and cook, undisturbed, until underside is very browned and you can see fat and juices start to pool on surface, 6–8 minutes. Toss lamb, using spatula to scrape it up and break into smaller pieces. Cook just to lightly brown rare side, 1–2 minutes more.