Mix the paprika, brown sugar, cumin, chili powder, ancho powder, garlic powder and 1 teaspoon salt in a small bowl.
Put the steak in a large resealable plastic bag. Add the juice of 1 lime, 1 tablespoon olive oil and the spice mixture; seal the bag and rub the spices into the meat. Refrigerate 30 minutes to 2 hours.
Meanwhile, heat a large cast-iron skillet over medium-high heat. Toss the bell peppers and red onions with the remaining 2 tablespoons olive oil, the juice of the remaining 2 limes and 1 teaspoon salt in a large bowl. Add to the skillet and cook, stirring occasionally, until the vegetables are tender and charred around the edges, 8 to 10 minutes.
Preheat a grill to medium high and brush the grates with olive oil. Grill the steak 3 to 5 minutes per side for medium rare. Transfer to a cutting board and let rest 5 to 10 minutes.
Warm the tortillas as the label directs. Slice the steak against the grain and season with salt. Serve on the tortillas with the onions and peppers; top with cheese and cilantro. Serve with lime wedges.
Photograph by Kang Kim
Courtesy of Food Network Magazine