In a large bowl stir together the lard or shortening, the butter, 1 cup of the sugar, the egg, and the vanilla. Into the bowl sift together the flour, the baking soda, and the salt and stir the mixture until it forms a dough. Chill the dough, covered, for at least 2 hours or overnight.
Preheat the oven to 375°F. Roll rounded tablespoons of the dough into balls, roll the balls in the additional sugar, coating them completely, and arrange them 3 inches apart on lightly greased baking sheets. Flatten the balls with the bottom of a glass dipped in the sugar (the edges will crack slightly) and bake the cookies in batches in the middle of the oven for 8 to 12 minutes, or until they are pale golden. Transfer the cookies to racks and let them cool. The cookies keep in an airtight container for 1 week.