In a large bowl, mix garlic, onion powder, sesame oil, coconut milk, pineapple juice, barbecue sauce, coconut aminos, olive oil, and red pepper flakes until well blended.
Set aside 1/2 cup of the marinade for basting the chicken on the grill.
Using a tenderizer, tenderize the chicken on both sides.
Place chicken and pineapple rings in a Ziplock bag or large low-line bowl, and pour the marinade on top. Gently incorporate into the chicken and pineapple rings, and allow to sit in the refrigerator for 15 minutes. [Marinating for more than 20 minutes isn’t good because the pineapple begins to get soggy.]
Grill marinated pineapple rings and chicken breasts for about 4-5 minutes on each side, making sure that they all reach an internal temperature of 165 degrees.
Serve hot with extra marinade and optional green onion garnish. Serve with a side of coleslaw and pineapple rings.