Heat 2 cast irons pan in oven at 450 degrees.
Prep veggies and meat- let meat come to room temperature and pat it dry with a paper towel.
Turn vent fan on high.
Turn stove on high, carefully move very hot cast iron pans from oven to stovetop.
Add oil to pans, swirl around.
Add meat to one pan, carefully (don't splatter oil when adding meat in, as it will be very hot!)
Add veggies to other pan.
Stir veggies and meat to prevent burning, but let them get a good browning on all sides- about 8 minutes.
If using taco/fajita seasoning, add to pan with 2 tbsp water, right before plating. Cook off any extra water.
Remove from heat and plate! If you want to create a "sizzle" sound like at a restaurant, splash a little water or a touch of soy sauce and oil in the pan.
Plate your salad with lettuce, tomatoes, beans. Layer fajita veggies and meat on top, and sprinkle shredded cheddar cheese over.
Dress with salsa, if preferred.