*Remove the flank steak from the refrigerator 30 minutes before grilling.*
Rub the fajita seasoning into both sides of the steak and allow it to rest for 30 minutes.
Heat a grill to 450ºF.
Place the steak on the grill and cook for 4-6 minutes on each side, until the internal temperature reaches the desired doneness.*
Remove the steak from the grill and allow it to rest for 5 minutes before slicing.
Heat the oven to 400ºF. Place the cast iron fajita skillets into the oven for at least 20 minutes in order to get a good sizzle.
While the fajita pans are heating, heat the oil in a skillet on the stovetop over medium heat.
Slice the onions and peppers into thin slices.
Add the vegetable slices to the hot oil and fry until they are tender, yet still crisp. Season with salt and pepper, to taste.
While the vegetables are cooking, slice the steak down the middle (if it is a wide steak), then slice it against the grain the size steak slices you'd like.
When the vegetables and fajita skillets are ready, remove the cast iron skillets from the oven adn quickly arrange the beef and peppers on it. It will immediately start to sizzle.
Serve the sizzling skillets with warm tortillas and other fajita toppings of your choice.
*Medium-rare (145 degrees F) Medium (160 degrees F) Well Done(170 degrees F)**The calories shown are based on the recipe making 6 fajitas, with 1 serving being 1 fajita and 1 tortilla. Since different brands of ingredients have different nutritional information, the calories shown are just an estimate. **We are not dietitians and recommend you seek a nutritionist for exact nutritional information. The information in the nutrition box are calculated through a program and there is room for error. If you need an accurate count, I recommend running the ingredients through your favorite nutrition calculator.**