Finely chop the onion, celery, carrot, parsley and apple (all well cleaned, washed and patted dry with kitchen paper); sauté in a heavy-bottomed, steel pan with 4 spoonfuls of olive oil and the butter (heat the oil first and then add the butter, so that it doesn’t burn). When the vegetables begin to colour, turn up the heat and add the minced beef, then add the chicken livers, which you have cleaned and chopped into pieces with a pair of scissors. Sauté the mixture, stirring continuously to prevent it from burning. When everything has browned, remove from the heat and chop the mixture finely on a chopping board; then put it back in the pan over the heat and add another tablespoon of olive oil. Season with salt, sprinkle with pepper (if you like it) and add a tablespoon of Pomarola, stirring well to incorporate it. At this point, add the “gottino” (= a typical Tuscan glass, equivalent to half a wine glass) of Vin Santo and allow it to evaporate slowly, stirring constantly.
Once the wine has evaporated, pour in the broth, add the cleaned and chopped anchovies, and simmer for another 10-15 minutes. Last of all, add the chopped capers, stir well again and remove the sauce immediately from the stove. It should have the consistency of a thick, coarse cream.
Spread it on thin slices of homemade bread (preferably the unsalted, Tuscan type) which, if you wish to follow tradition, you have toasted and dipped, quickly and only on one side, into some broth (ideally mixed with a little Vin Santo).
These crostini are prepared all over Tuscany, but you will hardly ever find any two that taste exactly the same – every cook, every trattoria has their own recipe!
Another idea: try spreading Salsa Nera on small slices of crispy, hot, fried polenta.