Heat a large skillet over a medium heat and fry the liver slices with some cooking fat until just browned. Set aside.
1 lb pork liver, Cooking fat
Add the onions to the skillet with more cooking fat if needed and cook until soft, about 6 to 9 minutes.
2 onions
Spread the soft onions on the bottom of a baking dish.
Make sandwiches by placing the apple slices and bacon halves between two liver slices. Place those in rows on top of the onions in the baking dish and season to taste with sea salt and black pepper. Pour the beef stock over the top.
4 slices bacon, 1 apple, Sea salt and freshly ground black pepper to taste, 1 cup beef stock
Place in the preheated oven to cook for about 30 minutes.