1 tablespoon baking powder
1 teaspoon baking soda
1 teaspoon salt
5 tablespoons cold butter, cut into 1/2-inch slices
3/4 cup plus 2 tablespoons buttermilk or yogurt
1. Heat the oven to 450°F. Mix together the flour, baking powder, baking soda, and salt in a large bowl. Add the butter and work it into the flour mixture, breaking it into tiny pieces with your fingers until the mixture looks like coarse meal.
2. Add the buttermilk and stir just until the mixture comes together and forms a ball. Spread some flour (about 1/4 cup) on a clean work surface and turn the dough out onto the flour. Knead the dough a few times, adding a little more flour to your hands only if the dough is very sticky.
3. Press the dough out 3/4 inch thick and cut out 1 1/2- to 2 1/2-inch rounds with a biscuit cutter or sturdy drinking glass. Put the rounds on an ungreased baking sheet. Press together the scraps, pat them out 3/4-inch thick, and cut out more biscuits. Repeat once more if possible.
4. Bake for 5 to 10 minutes, depending on size, until the biscuits are golden brown. Transfer the biscuits to a rack and serve within 15 minutes or wrap in foil and keep in a 200°F oven for up to an hour.