Preheat the oven to 425°F.
In a large bowl, whisk together 3 cups of the flour, baking powder and salt.
Blend 1/2 cup of the butter and the lard into the flour mixture using a dough or pastry blender. It will resemble course cornmeal, with pieces no larger than a small pea.
Pour half the buttermilk into the bowl and use a butter knife to gently stir it into the dough. Add more buttermilk, 2 tablespoons at a time, until there is no more dry spots remaining, but the dough should not be wet looking. (We ended up with 1/4 cup left in the glass, but you may have more or less depending on humidity.)
Gently press the dough together to form a rough ball. Take off pieces of the dough and form small balls, dipping your hands in the remaining 1/2 cup of flour, as Suvir shows in this short video. Melt the remaining butter in a 10-inch cast iron skillet. Place the biscuits in the pan and then turn them over, so the butter side is up.
Bake for about 20 to 25 minutes, or until golden brown. Let them cool for about 5 minutes before serving.