Peel the shallots and soak them in cold water. Finely chop the tail fat. Heat the sheet on low heat for 3-4 minutes. Add the lard to the heated sheet and fry it until it turns golden brown. Add cubed meat, salt and pepper to the melted tail fat and fry until the water is gone. When the meat starts to roast, add the shallots and continue to fry well. When the onions are cooked, serve the roasting sheet.