PREP/TOTAL TIME: 10 min In a large bowl, combine the flour, baking powder,, sugar, salt and cream of tartar; cut in shortening (or butter substitute) until mixture resembles coarse crumbs. If using the butter substitute, use 2/3 cup butter and reduce the salt by a 1/2 teaspoon. Store in an airtight container in a cool dry place or in the freezer for up to 6 months.