In a food processor or high-powered blender, mix together lime juice, coconut milk, cilantro, mango, salt, and garlic until thoroughly blended. Reserve ½ cup of the mixture. Place it in an airtight container and refrigerate until you’re ready to cook.
Add the remaining mango mixture to a gallon-size bag or airtight container. Add the chicken, then seal and shake until the chicken is entirely coated. Refrigerate 8 hours or overnight.
Rub your grill with olive oil so the chicken doesn't stick. Place chicken on your grill grates. Grill chicken over medium-high heat, basting with the reserved mango mixture until cooked all the way through (about 5-6 minutes on each side).
Serve immediately.
Notes
To freeze place the chicken and marinade in a freezer-safe bag or container, then seal and store for up to 3 months. Thaw it in the refrigerator overnight before grilling.