Place the olive oil, garlic and cilantro in a blender or food processor. Process until the mixture is combined and smooth. Scoop the marinade into the bag with the chicken, press the air out of the bag and zip it closed. Knead the marinade into the chicken until it is evenly distributed. Marinate overnight or all day long.
Preheat the grill to medium heat and coat with oil or grill spray. Remove chicken from the bag and grill 4 to 5 minutes on the first side, until good grill marks are showing. Flip and grill an additional 3 to 4 minutes, or until the chicken is cooked through.
Remove the chicken to a platter and brush the sweet chili sauce on top.
1/4 cup of minced garlic is quite a lot to mince yourself. I like to buy it already minced for this recipe - either fresh or jarred.
If you are preparing this recipe as gluten-free, just be sure to use a brand of chili garlic sauce that is known to be GF.