Heat the oil in a pan add the liver bacon and onion and fry them until the liver is brown and the bacon and onion are soft and just beginning to colour. Remove and add to the onion. Thinly slice the liver and pat it dry with kitchen paper. Rinse the liver in a colander under cold water and drain well on kitchen paper. Season to taste with salt and pepper.
Meanwhile mix the flour and sage if using and use to dust the liver. Remove from the pan then fry the onion until softened. Melt half of the butter with the oil in a large non stick frying pan over a high heat. Add the oil to the pan and brown the liver for about 1 min on each side. Add extra oil to the pan if needed and sauté a small amount of the liver at a time on a high heat and very quickly to seal in the juices.
Put the liver back in the pan and heat it through in the onion gravy for 2 3 minutes until hot stirring. Put the liver back in the pan and heat it through in the onion gravy for 2 3 minutes until hot stirring. Meanwhile mix the flour and sage if using and use to dust the liver. Serve the liver and bacon with a small portion of mashed potatoes and lots of freshly cooked greens. Heat the oil in a pan add the liver bacon and onion and fry them until the liver is brown and the bacon and onion are soft and just beginning to colour.
