01 - In a large bowl, whisk together olive oil, lime juice, garlic, smoked paprika, cumin, chili powder, oregano, salt, and pepper. Add the flank steak and toss to coat thoroughly. Cover and marinate in the refrigerator 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 let excess drip off before cooking.
03 - Place the steak on the hot grill and cook for 4–5 minutes per side for medium-rare doneness, adjusting time to your preferred level. Transfer to a cutting board, cover loosely with aluminum foil, and let rest for 5 minutes to allow juices to redistribute.
04 - While the steak rests, heat 1 tablespoon olive oil in a large skillet over medium-high heat. Add the sliced peppers and onions, season with salt and pepper, and sauté until tender and slightly charred, about 6–8 minutes.
05 - Place tortillas on the grill or in a dry skillet over medium heat for 30 seconds per side until warm and pliable.
06 - Slice the rested steak thinly against the grain into strips for maximum tenderness.
07 - Arrange grilled steak slices on a large platter with sautéed peppers and onions. Serve immediately with warmed tortillas, avocado, sour cream, salsa, fresh cilantro, and lime wedges on the side.