Begin by slicing the steak thin against the grain, aiming for even pieces that will cook quickly and stay tender. Set aside.
Next, slice the bell peppers and red onion into thin strips, creating colorful, uniform pieces that will caramelize evenly.
Heat a skillet over high heat until it’s just starting to smoke, then add the oil, swirling to coat the bottom of the pan.
Add the sliced peppers and onions to the hot skillet, and cook with a gentle sizzle, stirring occasionally, until they develop a smoky char and soften, about 5-6 minutes. The vegetables should be caramelized around the edges and fragrant.
Push the vegetables to one side of the skillet, then add the sliced steak to the empty space, spreading it out in a single layer. Let it sear for about 1-2 minutes without moving, until you see a deep brown crust form.
Flip the steak slices and cook for another 1-2 minutes, just until they’re browned and cooked through. Sprinkle with cumin, paprika, chili powder, salt, and pepper as the steak cooks, then toss everything together in the skillet to combine the flavors.
While the steak and vegetables finish cooking, warm the tortillas in a dry skillet over medium heat until they’re steaming and pliable, about 30 seconds per side.
Squeeze fresh lime juice over the cooked steak and vegetables for a bright, tangy finish, and give everything a final quick toss in the skillet to distribute the citrus flavor.
To serve, spoon the sizzling fajita mixture onto the warm tortillas, fold, and enjoy immediately while hot and flavorful.
