Salsa Verde

I first had salsa verde when I was a chambermaid in Florence. I was there with a schoolfriend and we used to go, most evenings, to a trattoria called Benvenuto, and eat tortellini in brodo, their penne al modo nostro, which involved an intensely garlicky tomato sauce, then moussey-sweet fegato or, my favourite, tongue with salsa verde. Now I wonder how good the restaurant was, but then, when most of the time we were living on a bottle of wine, a loaf of bread and a kilo