Prepare the Vegetables: While the steak is marinating, heat a skillet or grill pan over medium-high heat with a drizzle of olive oil. Sauté bell peppers and onion for 5–7 minutes until softened and slightly charred. Set aside.
Grill the Steak: Preheat your grill to medium-high. Remove the steak from the marinade and grill for 4–6 minutes per side, depending on desired doneness (130°F for medium-rare, 140°F for medium). Let rest for 5–10 minutes before slicing thinly against the grain.
Warm the Tortillas: On the grill, warm the flour tortillas for 1–2 minutes.
Assemble Fajitas: Fill each tortilla with sliced steak, sautéed peppers and onions, and optional toppings.
