Place the steaks, peppers and onions in a ziplock bag.
Stir marinade ingredients in a small bowl or ramekin. Add it to the other ingredients in the ziplock.
For a make-ahead meal, place in the freezer flat side down.
If cooking right away, let it marinate for an hour first or overnight.
Add the contents to a piping hot skillet with a dash of cooking oil and flip with tongs every 30 seconds or so. Once the meat has reached the desired doneness, remove it from heat.
Serve directly on the fajita skillet with warm tortillas.