Ingredients

a 1/4-ounce package active dry yeast (2 1/2 teaspoons)
1/4 cup warm water (about 105°F.)
3 tablespoons sugar
5 1/2 cups cake flour (not self-rising)
1 tablespoon baking powder
1 teaspoon baking soda
2 teaspoons salt
1/2 cup chilled vegetable shortening
1 stick (1/2 cup) cold unsalted butter, cut into pieces
1 1/4 cups buttermilk plus additional for brushing biscuits
3 tablespoons benne (sesame) seeds, toasted lightly and cooled

Method

1. In a small bowl stir together yeast, water, and a pinch sugar and let stand until foamy, about 5 minutes.
2. In a large bowl whisk together flour, baking powder, baking soda, salt, and remaining sugar.
3. With your fingertips blend in shortening and butter until mixture resembles coarse meal. Add yeast mixture and 1 1/4 cups buttermilk, stirring until a dough just forms, and gather into a ball (dough will be sticky).
4. On a lightly floured surface with floured hands knead dough gently 6 times and pat out into a 10-inch round (about 1/2 inch thick). Chill dough, wrapped in plastic wrap, at least 8 hours and up to 2 days.
5. Preheat oven to 425°F. and lightly butter a large baking sheet.
6. With a 2 1/2-inch round cutter dipped in flour cut out as many as possible and arrange, sides just touching, on baking sheet. Gather scraps into a ball and pat out dough. Cut out more rounds in same manner. Brush biscuits with additional buttermilk and sprinkle with benne seeds.
7. Bake biscuits in middle of oven 10 minutes, or until golden, and cool on racks.
8. Biscuits may be made 1 week ahead and frozen in sealable plastic bags. Thaw biscuits and reheat in a preheated 350°F. oven for 5 to 10 minutes or until heated through.