Preheat oven to 350F. In a food processor or large bowl, combine zest, flour, salt, pepper & sugar. Cut in the butter until you have mixture resembling coarse breadcrumbs. Mix in cashew butter, chopped cashews & water. Stir until a smooth dough forms. Wrap in waxed paper & chill for 1 hour. Once chilled, divide dough into 2 equal portions. Roll out to approximately 1/4" thickness. With a sharp knife, cut into 2" squares & transfer to an ungreased cookie sheet. Bake for 20 to 25 minutes or until golden brown. Cool on a wire rack.