Begin by making the marinade: In a large bowl, stir together the coconut milk, fish sauce, sugar, coriander, cumin, pepper, mustard, ginger, and fennel seed. Add the chicken. Cover and refrigerate for one hour. Also, soak your wooden skewers in water, for at least thirty minutes.
While the chicken marinates, make the Peach Dipping Sauce: Simmer all the ingredients for ten minutes in a three quart saucepan. Puree in a food processor. You can serve this warm, cold, or at room temperature.
After the chicken is marinated, thread the chicken on the skewers.
Heat a grill pan to high heat, and grill the chicken on both sides for about ten minutes, until the chicken is no longer pink inside. Serve with the peach sauce.