Combine soy sauce and dressing and pour over chicken in a large zipper bag. Seal and refrigerate at least 4 hours.
Preheat grill to medium heat.
Over medium heat in a heavy saucepan, melt butter and stir in soy sauce, brown sugar, garlic and hot sauce if desired. Mix until sugar crystals are dissolved. Set aside.
Cook the chicken on the grill, turning occasionally, until chicken is cooked through.
Place chicken in large bowl and pour the sauce over the chicken, tossing to coat.
If you like caramelized flavours, replace them on the grill for a few moments each side to brown further.