How to make
Soak the veal liver overnight in milk. Leave it in the refrigerator. The next day it is removed and very well dried in household paper and all veins, if any, are removed. Cut it into about 0.6″ (1.5 cm) slices.
Peel the onions and cut them into slices.
Melt a tablespoon and a half of butter and a little olive oil in a thick-bottomed pot over medium heat. Add the sliced onions, season with salt and leave it for 4-5 minutes on the stove to stew and stir often. It should soften, but not change its color - it should stay white. After that time, remove it from the heat and set it aside.
Pour olive oil into a large pan and fry the liver slices over a moderate heat. They are salted. They should aquire a nice golden color. Once they are ready, they are added to the onion and are left in a warm place.
In the same pan, add the last spoonful of butter, wine, by scraping the bottom from the sticky particles and it is left on medium heat to deglaze and reduce by half. In this sauce, add the liver with onions, season richly with as much balsamic vinegar as you like. Leave it for a few minutes on medium heat and the onion should blend well with the sauce.
Garnish: mashed potatoes
Note: In the original recipe, the liver is not soaked overnight in milk and it is directly washed, dried and prepared. As much balsamic vinegar as you like is added (about 3 1/3 tbsp (50 ml) is recommended).
I used quality Argentinian red wine.
