Fegato Grasso al Balsamico

This recipe is my contribution to the cooking of neighbouring Lombardy and Emilia-Romagna. It has been an incredible success in my Neal Street restaurant, impressing many French customers! The fegato grasso is produced in the area of Mortara in Lombardy, where many goose products come from. The sauce is ancient, dating back to Roman times. Saba is a strong reduction of cooked grape must, which, incidentally, is the first stage of the famous Emilian aceto balsamico; you