Mostarda is a trendy ingredient, found all over Italy, traditional in some northern regions like Piedmont, Veneto, Lombardia, Emilia-Romagna. Think of it like chutney. In Piedmont it's made of cooked winter fruit like quince, figs, pears, wine grape must and hazelnuts. It's called cugna', served with polenta, boiled meats, cheese or even snow. My favorite is made by Mongetto. In other regions mostarda is whole or minced candied, fruit or fruits, zapped with mustard essence. It's served with cheese or boiled meats.