If you want to lessen the gamey flavor, first rinse pieces and place liver into a bowl fillled with milk. Leave it for half an hour or an hour in the refrigerator.
Remove the liver from the milk and dry it. Heat the pan, sprinkle seasonings on both sides and fry the liver 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 fried, melt the butter in another pan and start frying the onion. Turn on low heat and stir. After 5 minutes, add sugar and mix, fry for another 3 minutes or until caramelizes.
Add chopped bacon, stir and fry for another 3 minutes. Transfer the fried liver to a plate. Put the fried caramelized onion with bacon on the liver and serve.