01 - Whisk together olive oil, lime juice, garlic, smoked paprika, cumin, chili powder, oregano, salt, and pepper in a large bowl. Add the flank steak and toss to coat thoroughly. Cover and refrigerate for at least 20 minutes, up to 2 hours for deeper flavor.
02 - Preheat a grill or grill pan over high heat. Remove steak from marinade and allow excess to drip off.
03 - Grill the steak for 4–5 minutes per side for medium-rare doneness, adjusting time to your preference. Transfer to a cutting board, cover loosely with foil, and let rest for 5 minutes.
04 - While steak rests, heat 1 tbsp olive oil in a large skillet over medium-high heat. Add sliced peppers and onions, season with salt and pepper, and sauté until tender and slightly charred, approximately 6–8 minutes.
05 - Warm tortillas on the grill or in a dry skillet for 30 seconds per side until pliable.
06 - Slice the rested steak thinly against the grain for maximum tenderness.
07 - Arrange grilled steak slices with sautéed peppers and onions on a large platter. Serve accompanied by warmed tortillas, avocado, sour cream, salsa, cilantro, and lime wedges.