In a gallon-sized resealable bag, pour in lime juice, vegetable oil, taco seasoning, garlic, and cumin. Mix well and then add chicken breasts. Place in fridge and let marinate for at least 30 minutes (although I highly recommend a at least 4-6 hours).
Remove chicken from marinade and discard marinade. Place chicken on a grill heated to medium-high heat. Let chicken cook until it is no longer pink on the inside (and has reached an internal temperature of 165 degrees F), turning as needed.
Serve chicken topped with pico de gallo or your favorite salsa.