Combine the coconut milk, nam pla, lime juice, garlic, shallots, hot sauce, red pepper flakes, sugar,
and cilantro in a blender or food processor and blend until smooth.
Salt and pepper both sides of the chicken and put it in a large plastic zip lock bag.
Pour the coconut mixture over the chicken and marinate it for 4 hours in the refrigerator, turning the chicken occasionally.
Prepare a gas or charcoal grill.
When the temperature is medium-hot, remove the chicken from the bag, and discard the marinade.
Place the chicken on the grill; cover and cook for about 8 minutes on one side.
Turn the chicken over and cook another 8 - 10 minutes, or until the internal temperature is 160 degrees.
Transfer the chicken to a platter and garnish with the scallions or Thai basil.
Serve at once with lime wedges on the side.