Whisk together olive oil, lime juice, garlic, lime zest, cilantro, salt, pepper and red pepper flakes.
Add chicken breasts and allow to marinate at least 30 minutes up to overnight.
Preheat grill to medium high heat. Oil grill grates prior to placing chicken on. Grill chicken for approximately 10 minutes, flipping halfway thru, or until chicken reaches a temp of 165°F.
Serve with a side salad, sliced avocado, rice or black beans.