Dissolve the yeast and a pinch of sugar in the warm water. Into a large bowl sift the baking soda, baking powder, salt, and the remainder of the sugar, with 6 cups of the flour. Cut the shortening into the dry ingredients with two forks, a pastry cutter, or your fingers until the size of garden peas. Add the yeast mixture to the buttermilk and stir into the flour mixture until all the flour is barely moistened to make a sticky dough. Cover with plastic wrap and refrigerate overnight or up to a week before using.
When ready to cook, preheat the oven to 425°F.
Place about 1 cup additional flour on the work surface. Place the sticky dough on top of the flour and sprinkle with more flour. Pat out into a round 1/3 inch thick and then fold over to a height of 2/3 inch. Using a 2 1/2-inch biscuit cutter, cut out the biscuits. If you desire a 1 1/2-inch round, make the dough thinnera total of 1/2 inch. Place the biscuits, their sides touching, on the baking sheet. Bake 10 to 12 minutes, until lightly tinged with brown.
The biscuits can be kept frozen up to 3 months.
Nathalie Dupree's Comfortable Entertaining by Nathalie Dupree Viking