Venetian Liver

This is one of my favorite liver recipes. I have two favorite ones and the other one is a Turkish recipe.  Next liver recipe I write will be for sure the Turkish one, but this time I am writing about the Venetian liver.  Venetian liver recipe is a classic and you can find in many Italian restaurants.  This is a recipe that I adapted from a German version that I found somewhere.  I used veal liver to make this one.  In the meantime I found some other versions on the web. This one on the Epicurious site here looks like a good one too but I haven't tried it yet.  If you want to give it a go please let me know what you thought of it.
I made some rice with this one but you can have it also only with some bread, because it tastes really good. 

Venetian Liver

500 gr liver from veal, sliced.
2-3 medium size red onions, sliced
1-2 sage leaves
50 ml Balsamic vinegar
20-30 ml red wine
1 tablespoon butter
2 tablespoon olive oil
salt and pepper to taste
a handful of chopped parsley

Make sure you have everything ready before you start, because you have to cook everything really fast over high heat.
Start with heating butter and olive oil in a pan over high temperature. When it's hot enough, put in the liver and stir-fry it for about a minute.  Take it out and put it on a plate.  Don't worry if it's not cooked, it is supposed to look still red and raw.  If you want the liver to stay soft do not ever overcook it.  After you take the liver out of the pan, put in the onions and fry them until they are soft and slightly brown.  Add the balsamic vinegar, wine and the sage leaves.  Reduce the heat to medium and cook it for another 2-3 minutes.  Add the liver back in and cook for another minute or two.  Add some salt and pepper before you taste.  Liver should stay soft like this and it will be cooked enough.  Before you serve it sprinkle some chopped parsley on top.  Enjoy it with some rice or bread.