Pour the buttermilk into a small bowl. Add the yeast and stir to dissolve. Let stand for 5 minutes or until the mixture bubbles. In a large bowl, stir together 2 ½ cups flour, sugar, baking soda and salt. Add the buttermilk mixture and oil to the flour mixture. Stir gently and quickly until mixed. Lightly flour a flat surface. Turn out the dough. Knead gently 20 to 30 times. Roll out or pat to ¼ inch thickness. With a floured 1-inch biscuit cutter, cut out 60 biscuits. Lightly spray each biscuit with vegetable oil spray. Lightly spray a baking sheet. Put 30 biscuits on it. Put a second biscuit on top of each. Cover with a dry dish towel. Let the dough rise in a warm, draft-free place (about 85 degrees F) for about 2 hours. Preheat the oven to 375 degrees F. Bake for 12 to 15 minutes. | 
