Preheat oven to 400 degrees F.
Leave 2 tablespoons of drippings in the roasting pan and place in the oven.
Place the flour, salt, eggs, milk and remaining 2 tablespoons of drippings into the bowl of a food processor or blender and process for 30 seconds. Pour the batter into the hot roasting pan and bake for 35 to 40 minutes or until puffed and golden brown. While the pudding is cooking, carve the roast. Serve the pudding with the roast.
A 3-bone-in standing rib roast cooked in a 13 by 9-inch roasting pan will give you enough drippings for the pudding. Prepare the pudding while the roast is resting.
Recipe courtesy of Alton Brown, 2008