Preheat oven to 400°F (200°C).

Sift together flour, sugar, baking powder, soda, and salt in a large bowl.

Cut in shortening using a pastry blender or your fingers until the mixture resembles coarse crumbs.

Dissolve yeast in warm water.

Add the yeast mixture and buttermilk to the flour mixture.

Mix until just combined.

Turn the dough out onto a lightly floured surface.

If necessary, add additional flour to make a soft, manageable dough.

Roll out the dough to 1/4-inch thickness.

Cut out biscuits using a biscuit cutter or knife.

Dip each biscuit in melted butter and fold over to make pocket-book rolls.

Place biscuits on a baking sheet.

Bake for 10 to 12 minutes, or until lightly browned.

Store unused dough in a plastic bowl in the refrigerator for up to a week.