Wash chicken livers and pat dry with towel. Set aside. Cut up chicken fat and put in a skillet with onions. Saute, stirring occasionally, to prevent burning the onions. Cook until the onions are lightly browned and fat is melted. Remove onions and set aside. Pour liquid chicken fat into a cup and set aside. Place livers in the same skillet with 3 tablespoons of the liquid chicken fat and saute until well done. Add additional chicken fat, if necessary. Cool slightly. Using a food grinder with a fine blade, a food blender at high speed, a food processor with a metal blade, or a chopping bowl, finely grind or chop livers, hard-cooked eggs, and onions. Place mixture in a bowl, add salt, pepper and about 1/4 cup liquid fat. If additional fat is necessary, add salad oil, one tablespoon at a time, to the mixture. Mix until all ingredients are well blended. Fill a well-oiled 3-cup mold or shape into a simple ball and refrigerate. Serve with cocktail-size rye bread slices. Makes 3 cups.