Rub steaks with the fajita seasoning. Grill steaks about 3 to 4 minutes per side. Set aside.
Heat a cast iron pan over medium heat. Add olive oil and butter. Saute onions and garlic until starts to brown then add the bell peppers and saute for another 5 minutes. Season with salt and pepper. Transfer to a plate.
Heat the tortillas on another pan for about 1 minute per side and stack them on a plate. Thinly slice the steaks. Serve fajitas with cilantro and lime wedges.
Recipe by The Gluten Free at https://www.theglutenfree.com/gluten-free-grilled-steak-fajitas/