I adapted this from a Martha Stewart recipe. Most folks look down on Crisco, but the Crisco/butter combo in this recipe gives great results. I keep it in the cupboard just for biscuits.
3 C. Flour (If you can get White Lily, great. I use bleached All Purpose & it's fine)
1 T. baking powder
3/4 t. baking soda
3/4 t. salt (regular table salt, not kosher)
5 T. butter, diced and chilled
3 T. Crisco, diced and chilled
1 1/2 cups of buttermilk, or more depending on the weather
flour for dusting work surface
Preheat oven to 425F
Sift dry ingredients and put into the bowl of a large food processor with the sharp blade attachment. Add butter and Crisco, and give approximately 5-10 pulses, until the fat is in very small pieces but not completely worked into the flour. Turn out into a very large bowl and add buttermilk. If it looks like it's going to be too dry, add more buttermilk, but don't wait too long. Better that the dough be too sticky than dry and falling apart. Chill in the refrigerator for 15-20 minutes.
Dust a work surface heavily with flour and turn out the dough. Sprinkle flour on top of the dough, then fold it in half and give a quarter turn. Sprinkle a little more flour, fold in half, and turn again. Once it's absorbed enough flour to handle without sticking all over your hands, knead and turn a few more times to get layers. Pat out into a thick circle, and cut rounds with a very sharp, floured biscuit cutter. Don't twist the cutter, or the biscuits won't get their full height. Place on a baking sheet - not touching! - lined with parchment. Bake for about 15 minutes.