Depending on their size, cut each chicken thigh fillet into 4 to 6 pieces.
In a large bowl, place the rest of the ingredients. Beat with a wire whisk until smooth. Add the chicken pieces, mix well, rubbing the marinade into the meat with your hands. Cover the bowl with cling film and place in the fridge for at least two hours.
While the chicken marinates, soak 12 to 18 bamboo skewers in water to prevent them from burning on the grill.
Thread the marinated chicken in the bamboo skewers (5 pieces per skewer is a good number).
Make the dipping sauce. In a small sauce pan, simmer the remaining marinade until thickened, about 15 minutes.
Grill the chicken at least six inches from the heat (peanut butter burns fast), 4 to 5 minutes per side depending on the size of the chicken pieces.
Serve the grilled chicken satay with the dipping sauce on the side.