Place chicken breasts in a mixing bowl, baking dish, or plastic bag. You'll need something that can be covered/closed so the chicken can sit in the marinade.
Next, create the marinade. In a small mixing bowl, combine the olive oil, cilantro, garlic, lime juice, lime zest, cumin, salt & pepper. Mix until combined. Pour marinade over chicken and ensure all chicken gets coated with marinade.
Cover chicken and place in refrigerator. Let chicken marinade for a minimum of 30 minutes, but you can marinade overnight as well.
When ready, preheat grill to 400-425 degrees F. Take chicken out of fridge and allow to sit at room temp while grill is preheating (this helps the chicken to cook more evenly and create even juicier chicken).
Grill chicken on each side for roughly 6-8 minutes, or until internal temperature at the thickest part reaches 165 degrees F. Total cooking time will vary pending how large your chicken breasts are.
Notes
If my chicken breasts are on the larger side I usually cut them in half. They will cook faster this way, and I find they retain their juices better.
You can sub chicken thighs for the chicken breasts if you’d like. Chicken thighs take longer to cook than chicken breasts, so use a meat thermometer to ensure you cook the thighs to 165 F. The total cooking time will depend on how large the thighs are.
You can easily bake this chicken too. Preheat oven to 400 F and bake until internal temperature reaches 165 degrees F. This will take roughly 20-25 minutes, depending on how large your chicken breasts are.