Mix all marinade ingredients together in a bowl.
Marinade the chicken cutlets in a gallon Ziploc bag for at least two hours, preferably overnight.
Slice the tomato and avocado into small cubes and the jalapeno into thin slices.
Pull off enough cilantro leaves for each taco.
Remove the chicken from the marinade and cook on a pre-heated cooking grate over the hottest part of the fire.
Brown each side of the chicken, then move it to a cooler part of the grate to finish cooking.
Let the meat rest for about 5 minutes after cooking.
Cook the tortillas on the grate one or two at a time, avoiding burning.
Slice the fajita meat thin across the grain.
Serve all ingredients buffet style for everyone to build their own fajitas.