Instructions:
- Pat the flank steak very dry with kitchen paper. Slice the steak thinly against the grain into strips (about ¼ inch thick). Freeze for 15 minutes beforehand if needed for easier slicing.
- In a bowl, whisk together all marinade ingredients (lime juice, olive oil, chili powder, cumin, smoked paprika, oregano, salt, pepper, and garlic). Add the steak strips, toss well to coat, cover, and refrigerate for at least 15 minutes.
- While the steak marinates, slice the onion and peppers into thick strips. Warm the tortillas according to package directions and keep them warm wrapped in a clean tea towel.
- Heat 1 Tbsp of cooking oil in your large skillet or cast-iron pan over medium-high heat until shimmering. Add the onions and peppers. Sauté vigorously for 5–7 minutes until tender-crisp and slightly charred. Remove vegetables from the pan and set aside.
- Increase the pan heat to high. Remove steak from the marinade, letting excess drip off, and sear in batches if necessary to ensure searing rather than steaming. Cook for 1–2 minutes per side until beautifully browned.
- Return the seared vegetables to the pan with the steak. Toss everything together quickly for 30 seconds to incorporate any juices and reheat. Taste and adjust seasoning.
- Serve the sizzling steak and pepper mixture immediately alongside the warm tortillas and desired toppings.