1Heat the oven to 450 F and set a rack in the upper third. Line a rimmed sheet pan with foil.
2Pat the steak dry and slice it across the grain into strips about 1/4 inch thick. Toss in a bowl with 1 tbsp of the oil, the lime juice, half the garlic, and a pinch of salt.
3In a small bowl, stir together the chili powder, cumin, smoked paprika, oregano, 1 tsp salt, and a few grinds of pepper.
4Spread the peppers and onion on the sheet pan. Drizzle with the remaining 2 tbsp oil, sprinkle with half the spice mix, and toss to coat. Roast for 10 minutes.
5Push the vegetables to the edges. Spread the steak in the center in a single layer, sprinkle with the remaining spice mix, and roast 6 to 8 minutes, until the steak is browned at the edges and the vegetables are charred.
6Let the steak rest 3 minutes on the pan. Toss everything together with the remaining garlic and a squeeze of lime, then pile onto warm tortillas and top with cheese, cilantro, and lime wedges.