Chop up your cilantro, zest and juice up your limes, mince your garlic and chop your red onion into small chunks.
You can either mince your red onion by throwing it into a food processor or mince it by hand. I find it easier to just throw it in the processor, and let it do the work
In a medium bowl, mix together the lime zest and juice, olive oil, minced garlic, cumin, minced red onion, red pepper flakes, chopped cilantro and a pinch of salt and pepper.Put the chicken breasts into a ziploc bag and pour in the mixture. Zip up the bag, and give it a couple of shakes to make sure that all of the chicken breasts are evenly coated.
Put the bagged chicken in the refrigerator and let it marinate for 2-4 hours or up to 6 hours.
Note: I wouldn’t recommend marinating the chicken breasts for more than 6 hours, as they will get a bit rubbery. If you want to make this a true make ahead meal and marinate it for more than 6 hours, then you can pick up some boneless chicken thighs. They will take in the marinade beautifully and can handle marinating overnight or for more than 6 hours.
Once the chicken has marinated, call upon your grill master (that would be my husband) to get the grill nice and hot. Grill the chicken breasts about 7 minutes per side or until thoroughly cooked (when they reach an internal temp of 165 degrees). Chicken breasts vary is size so it usually takes longer than 7 minutes per side, that is why I always test my chicken with a meat thermometer.
Let the meat rest for at least 5 minutes, and then slice the chicken breasts into thin slices.
While the chicken is resting, throw the tortillas on the grill, and grill them until slightly charred and pliable, about 20 seconds per side.
These tacos are not complete without the mango avocado salsa, seriously, it adds so much flavor.
Top each tortilla with the sliced chicken, mango avocado salsa, cotija cheese or queso fresco and some fresh cilantro.