Preferably, in an earthenware pan, heat oil and butter together. Add the chopped onion. Cook on medium heat until the onion turns golden.
Clean and wash the livers well, and toss them in the pan with the sage. Add the livers to the pan, and cook with the pan covered to release the cooking water from the livers. Then add the wine after a couple of minutes. Cook over low heat for 15-20 minutes slowly adding the chicken broth.
It is essential that the sauce does not dry out and that you retain the broth. When the livers are almost cooked add the capers and anchovies. Make sure you have cleaned the bones from the anchovies.
To mince the livers, use a large kitchen knife. Some use kitchen mixers or food processors to mince the livers; if you choose this option, the livers will turn into a spreadable paste ideal for use on Tuscan bread.
During the preparation of the minced livers with the mixer or food processor, remember to add salt and pepper, continuously adding diced livers until a liver pate is formed.
Following the Tuscan tradition, the resulting paste must be spread, while still hot, on Tuscan bread that has been soaked in broth.