Combine brown sugar and the following eight ingredients in a blender and puree until smooth. The last time I made this, I forgot to blend the ingredients, and it turned out fine.
Combine chicken and marinade in a bowl or plastic bag. The original recipe called for one hour, but I prefer overnight.
Grill chicken and season with salt and pepper. Use a meat thermometer and grill to an internal temperature of 165.
Remove and let sit for five minutes. Slice the chicken on an angle and serve. I like to serve this with thick udon noodles smothered in peanut sauce. That recipe will be posted next. You could also serve it with rice.