First, slice all the bell peppers and the mix together the fajita seasoning. You can also purchase a fajita seasoning from the store if you don't have all the individual spices. Preheat the oven to 400℉.
Now, do not cut the steak before cooking. Thin pieces in the oven will cook super fast and you'll have dry meat. Note, if you want a steak that's not well done you'll need to pull it out earlier than the cook time and leaving the veggies to finish cooking.
Seasoning the steak with the fajita seasoning first. Then, with a little oil toss the sliced bell peppers and onions in the remaining seasonings. Layer everything in the sheet pan. Then, bake for 25 minutes.
Remove the sheet pan and squeeze a lime over the ingredients. Serve with you favorite tortillas and maybe even a little Mexican rice