Finely chop the onion, celery, carrot, parsley and apple (well cleaned, washed and patted dry with kitchen paper); sauté in a heavy-bottomed, steel pan with 4 spoonfuls of olive oil and butter. When the vegetables begin to colour, add the minced beef and brown, then add the cleaned chicken livers, which you have chopped up coarsely with a pair of scissors. Allow the mixture to brown, stirring continuously to prevent it from burning. When everything is browned, remove from the heat and chop up the mixture finely on a chopping board; then put it back in the pan over the heat and add another tablespoon of oil. Season with salt, sprinkle with pepper (if you like) and also add a tablespoon of Pomarola, stirring well. At this point, add the “gottino” (= 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 cook for another 10-15 minutes. Last of all, add the chopped capers, stir well and remove the sauce immediately from the heat. It should have the consistency of a thick, coarse cream.
Spread it on thin slices of homemade bread (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 rarely find any two which 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.