2Sift together the flour, sugar, baking soda, and salt into a large bowl. Rub in the shortening until the mixture appears sandy. Stir in the buttermilk until the dough holds together. Roll out on a lightly floured surface to 1/8-inch thick. Cut into 4-inch squares, then cut each square diagonally into triangles, and prick with a fork.
3Bake the triangles in preheated oven on ungreased cookie sheets until dry and lightly browned, about 10 minutes.