Use rubber gloves to mince the chiles and place into a mixing bowl. Add cilantro, garlic, vegetable oil, vinegar, lime juice, salt, and black pepper. Mix piri piri sauce well.

Place chicken breasts and legs into a resealable plastic bag. Pour in piri piri sauce, seal the bag, and shake gently to completely cover chicken. Put the bag in the refrigerator to marinate at least 4 hours.

Remove bag from the refrigerator about 30 minutes before cooking to allow chicken to come to room temperature.

Preheat an outdoor grill for medium heat and lightly oil the grate.

Remove chicken from the bag; discard bag and cilantro. Cook chicken on the preheated grill, rotating as necessary to cook evenly, until juices run clear and an instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C), about 25 minutes.