Pulse flour, lard, sugar, and salt in a food processor until you have flour-covered pea-sized pieces, about 15 quick pulses. Add buttermilk all at once and process until the wet dough almost comes together.
Generously flour work surface and scrape dough out onto it. Turn dough over to coat. Gather and fold dough over on itself a couple of times, then pat into a soft 4x6-inch block.
Crisscross 2 long pieces of plastic wrap to form an X and lightly dust with flour. Place dough in the center and wrap tightly. Smooth wrapped surface with rolling pin; flip and repeat. Chill at least 4 hours or preferably overnight, or slip into a zip-top plastic freezer bag and freeze up to 3 months. Thaw overnight in the fridge before using.