Marinate the chicken first! At least 30 minutes ahead of time (or even the night before), combine the chicken with the olive oil, lime zest, garlic, smoked paprika, cumin, salt and pepper. Place in in a dish or resealable bag and stick it in the fridge.
When you’re ready to grill, remove it from the fridge about 30 minutes before. Preheat your grill to the highest heat for 10 minutes.
Once the grill is hot, place the chicken on the grates. Grill about 5 minutes per side, until golden and charred and the internal temperature reaches 165 degrees F. Let the chicken rest for 10 minutes.
While the chicken cooks, make the slaw. In a large bowl, combine the cabbage, lime zest, shallot, garlic and cilantro. Add the lime juice and olive oil. Sprinkle on the sugar, salt and pepper. Toss well, mixing over and over to make sure everything is combined. Let the slaw sit while you finish the tacos.
Once the chicken rests, chop it up. Fill the tortillas with the chicken and if you wish, some avocado. Drizzle with sour cream. Top with the key lime slaw, a few radish slices and cotija cheese. If you want, sprinkle with a bit of tajin or smoked paprika. Enjoy!