I used to hate liver, probably because of a run-in I had with some that wasn’t cooked very well when I was a wee lad. That all changed when I started working in restaurants and cooking liver regularly. I became much more used to the flavour and aroma, and I grew to enjoy it. Liver and onions are a classic diner dish, slightly elevated here with the addition of balsamic vinegar.
Before you begin, be sure the membrane and any traces of the arteries have been removed from the liver. Place the liver in a bowl with the milk and refrigerate for 1 hour. Discard the milk and pat dry the liver on a towel.
Melt 2 Tbsp of the butter in a large pot over medium-low heat. Add the onions and bacon, cover, and simmer, stirring frequently, until the bacon is brown and the onions caramelized, at least 1 hour. Season with salt and pepper, remove from the pot, and set aside.
Place the flour in a shallow bowl. Season the liver with salt and pepper, then dredge the slices in the flour, shaking off any excess, and place them on a plate. Melt the remaining 2 Tbsp butter in a large frying pan over medium-high heat. Add a few slices of liver, brown them on the outside, and transfer to a clean plate. Repeat with the remaining liver.
Add the onion and bacon mixture and the sage to the frying pan. Pour in the vinegar and Worcestershire sauce and bring to a simmer. Add the browned liver and stir until well combined.
To serve, divide the liver and onions among individual plates and serve immediately with your favourite mashed potato recipe.
One of the reasons most people don’t like liver is because it has been cooked to death. Liver, whether beef, veal, or poultry, can be served slightly pink, but I prefer when it’s been just cooked through (160°F internal temperature). Overcooked liver develops a mealy texture. When thinly sliced, liver just needs a quick sear, followed by a minute of reheating in the sauce.