In a small bowl combine yeast and sugar in water. Set aside for 10 min. In a large bowl mix flour, sugar, baking powder, soda and salt. Cut in butter to form a crumbly mixture. Stir in yeast mixture and buttermilk. Mix just enough to hold dough together. Roll dough 0.75 in. thick on floured surface. Cut out biscuits with the top of a glass or a cutter. Prick tops with fork. Freeze separately on cookie sheet. After biscuits are frozen, stack and wrap well. Before baking let rise until doubled in size. Bake at 220ºC for 15 mins. on a lightly greased cookie sheet.
Makes 3-4 dozen. Grated Cheddar cheese may be added to soft dough for flaky cheese biscuits.