01 - In a bowl, combine the sliced beef with olive oil, lime juice, garlic, cumin, smoked paprika, chili powder, salt, and black pepper. Mix well, cover, and marinate for at least 15 minutes (or up to 2 hours in the refrigerator for more flavor).
02 - Heat 1 tbsp olive oil in a large skillet or grill pan over medium-high heat. Add the peppers and onion, season lightly with salt, and sauté for 5–6 minutes until just tender and slightly charred. Transfer to a plate and keep warm.
03 - Add the marinated beef to the same skillet. Cook for 3–4 minutes, stirring occasionally, until browned and cooked through.
04 - Return the peppers and onions to the skillet with the beef. Toss together for 1 minute to combine and heat through.
05 - Warm the tortillas in a dry skillet or microwave.
06 - Serve the beef, peppers, and onions in the tortillas. Garnish with cilantro and a squeeze of lime. Add salsa, guacamole, or sour cream as desired.