Preheat oven to 450 degree F. Grease large baking sheets; set aside. In a very large mixing bowl stir together flour, baking powder, baking soda, and salt. Using a pastry blender, cut in butter until mixture resembles coarse crumbs. Stir in sage. Make a well in the center of the dry mixture. Add buttermilk all at once. Using a fork, stir just until moistened.
Turn dough out onto a lightly floured surface. Knead dough lightly for 10 to 12 strokes until nearly smooth. Lightly roll dough to a 15x9-inch rectangle about 1/2 inch thick. Cut dough into 1-1/2-inch diamonds. Sprinkle with additional flour. Or combine egg white and water; brush biscuits with mixture and sprinkle with ground sage, sesame seeds, and/or white pepper. Place biscuits 1 inch apart on an ungreased baking sheet. Bake in preheated oven for 10 to 12 minutes or until golden.
Remove biscuits from baking sheet to a wire rack; cool. Arrange in covered containers and freeze up to 1 month. To serve, thaw at room temperature for 1 hour. Split biscuits and arrange on serving trays. Makes about 48 biscuits.