Cut the skirt steak into 3 equal size pieces and place in a gallon-sized resealable bag.
Combine the olive oil, lime juice, soy sauce, salt, chile powder and cumin in a bowl. Reserve about 1/4 cup marinade in a squeeze bottle for later use, then pour the rest into the bag with the steaks. Seal the bag and press out all the air, making sure all sides of the steaks are evenly coated. Refrigerate for at least 30 minutes.
Remove the steaks from the bag and shake off any excess marinade. Place on a wire rack-lined baking sheet and return to the fridge, uncovered, for another 2 hours. (This will make sure the steaks get a beautiful rich color when seared.)
Heat a 12-inch cast-iron skillet over medium-high heat. Add 1 tablespoon canola oil. Give the steaks a generous sprinkle of salt, then put in the hot skillet. Sear until a crust has developed, 2 to 3 minutes per side. Remove to a cutting board. Without cleaning the skillet, add the remaining tablespoon canola oil, followed by the peppers and onions, and cook until slightly softened, 5 to 6 minutes.
Meanwhile, slice each steak in half with the grain. Now turn the steaks 90 degrees and slice against the grain into 1/4-inch strips. When the peppers and onions are almost finished cooking, add the steak to the hot skillet for a final sizzle and season with salt and pepper. Squirt the reserved marinade into the hot skillet to create a steamy sizzle. Serve with the tortillas and any toppings you wish.