November 18, 2012 The Elusive Cavolo Nero (Black Kale): Black Kale, Sweet Potato and Cheddar Gratin Food / Recipes / Regions of Italy / Tuscany / Vegetables, Side Dishes 1 Ahhh, the elusive cavolo nero! This mysterious green is an essential ingredient for authentic ribollita – a Tuscan soup made with tomatoes, beans, kale and …