Wash and pat dry chicken pieces then season with salt and pepper, add to a large bowl then pour enough brine to cover the chicken. Chill for 3 to 12 hours. Tip: Use your favorite brine for this but pineapple-based brine really fits in with the tropical theme.
In a Dutch oven heat, the butter and olive oil then fry the onion until soft.
Reduce or remove the onion from heat then add the Mango and chili letting it soften slightly with residual heat.
Mix the drained chicken pieces into the mango mixture then cook in your Dutch oven over coals or in a BBQ at around 225 degrees F (110 degrees C) until the internal temperature of the chicken is at least 74 degrees C (165 degrees F).
Once the chicken is ready, plate the chicken and cover it with foil. Add the coconut milk to the remaining mango and chili mixture then heat through. Serve the coconut mango sauce over top of the chicken.