In a medium-size bowl cream together the sugars, peanut butter and shortening. In a small cup dissolve the baking soda in the water, add the vanilla and egg, slightly beat together and stir into the creamed mixture. Add the flour and mix well.
Roll dough into 2 1/2 balls or drop from cookie scoop onto an ungreased cookie sheet. Flatten with a fork or meat mallet which has been dipped in flour. Bake at 375 degrees for 10-12 minutes or until lightly browned. Remove to rack to cool.