Rinse pieces, blot dry with paper towels and place liver into a bowl filled with milk. Leave it for half an hour or an hour in the refrigerator. Remove and dry each piece with paper towels.
Heat the pan over medium heat, season with seasonings on both sides of liver pieces and fry pieces in oil for 5 minutes on one side. If the pieces are thin, then you can fry for 3-4 minutes. Flip over and fry the liver for another 4 minutes.
While the liver is frying, melt the butter in another pan and start frying the onions. Turn on low heat and stir. After 5 minutes, add sugar and mix, fry for another 3 minutes or until caramelized.
Add chopped bacon, stir and fry for another 3 minutes. Transfer the fried liver to a plate with bacon/onion mixture on top and enjoy.