Combine flour, soda, and salt in a large mixing bowl; cut in butter, lard, and egg with a pastry blender until mixture resembles coarse meal. Add buttermilk, stirring well.
Turn dough out onto a floured surface. Pound dough with a wooden mallet or rolling pin for 20 minutes or until surface is covered with air bubbles, folding dough over frequently.
Roll dough to 1/8-inch thickness, and cut into 2-inch squares. Place on well-greased baking sheets in even rows, and prick tops of squares with tines of a fork. Bake at 400° for 15 minutes or until lightly browned. Remove crackers from baking sheets, and serve with soups or stews.