Place chicken in a ziploc bag or shallow container. Cover in Sweetwater Spice Lime Jalapeño Fajita Bath and refrigerate for at least one hour. Strain marinade, reserving the solids, and rub the thighs with the solids.
Grill the chicken over indirect heat until it reaches an internal temperature of 165°F (check the temperature using an instant read thermometer like the Maverick). Pull, cover and rest 10 minutes before slicing. Meanwhile, on a hot griddle/skillet, sauté the onions and peppers, seasoning with the Cattleman's Grill Carne Asada Seasoning, until onions begin to caramelize.
Slice chicken. Serve in tortillas with your desired toppings, such as chopped cilantro, guacamole, sour cream, cheese, etc.