Pre-heat a grill pan or grill to medium-high.
Pre-heat oven 200°F. Wrap tortillas in a clean, wet, kitchen towel and place in oven to get warm.
Drizzle steak with EVOO.
Season the steak with cumin, chipotle powder, salt and freshly ground black pepper. Place the seasoned flank steak on the grill or grill pan and cook until the meat is well-browned on one side, about five minutes. Turn and continue to cook until well-browned on the other side and medium-rare at the center, about four minutes more. Transfer the steak to a cutting board and let rest for several minutes.
While the steak is cooking, pre-heat a large, nonstick skillet over medium-high heat. Add vegetable oil, about two turns of the pan, and let the oil start to smoke. Add the cabbage, bell peppers and red onions, toss and cook them until the veggies soften and cabbage starts to wilt, about 7-8 minutes. Season the veggie mixture with salt, freshly ground pepper, hot sauce and juice of one lime.
Remove from the heat and keep warm.
Thinly slice the steak across the grain and transfer to a warmed platter along with the spicy veggies. Serve with scallions, avocados, sour cream and lime wedges alongside as your toppers. Top the warm tortillas with a couple of slices of meat, spicy veggies, some smoked cheddar on top and whatever additional toppings you want!