Start by patting the sliced steak dry with paper towels, then season with salt, pepper, cumin, and smoked paprika to enhance the flavor.
Heat your skillet over high heat until shimmering, then add a tablespoon of oil and swirl to coat the bottom.
Once the oil is hot and slightly smoking, carefully place the steak slices in the pan in a single layer. Sear for about 2-3 minutes without moving, until a deep brown crust forms, then flip and sear the other side.
Remove the seared steak from the skillet and let it rest on a plate for a few minutes to retain juices, then slice into thin strips against the grain.
In the same skillet, add another splash of oil if needed, then toss in sliced peppers and onions. Cook, stirring occasionally, until they soften, char slightly, and release a smoky aroma—about 5-7 minutes.
Squeeze fresh lime juice over the vegetables and stir to combine, brightening the flavors and deglazing the pan for extra flavor.
Warm the tortillas in a dry skillet over medium heat until lightly toasted and pliable, about 30 seconds per side.
Assemble the fajitas by spooning some of the cooked peppers and onions onto a tortilla, then topping with sliced steak.
Serve your steak fajitas immediately, with extra lime wedges on the side for an added zing.