Marinate the steak in the fajita seasoning, olive oil and lime juice for at least 30 minutes, or up to 24 hours (this is a great meal to prep in advance!)
Cook the steak in a cast iron skillet, about 2-3 minutes per side over medium-high heat.
Once the steak has finished cooking, allow it to rest, then slice into thin strips.
In the same skillet, add the remaining oil and saute the onions and bell peppers until they become tender, and slightly charred.
Assemble the nachos! In the same cast iron skillet, arrange the tortilla chips in a layer on the bottom and top with some of the shredded cheddar
Continue layering the peppers and onions, sliced steak, and a generous sprinkle of shredded cheddar cheese.
Broil the entire skillet in the oven for about 2-4 minutes, or until the cheese is melty and bubbly.
Add the toppings and serve!
Watch the nachos carefully under the broiler - they can go from done to burnt in an instant!