Mix water and soy sauce together and set aside. Mix flour, salt and pepper together in plastic or paper bag. Sautee bacon slices, sliced mushrooms and onions in cooking oil and set aside.
Cut liver into desired size pieces and coat the liver pieces with the flour mixture. Add more cooking oil to fry pan if needed, and brown the liver on both sides over high heat.
When all liver is browned, turn the heat down to medium, pour soy sauce mixture over the liver, cover and simmer until liver is NOT pink inside. Add the bacon, onions and mushrooms mixture with the liver.