At some delis beef liver is used, but in my family we always make it with chicken liver. The liver is broiled, not sauteed, because broiling is necessary to remove the blood to make it kosher, instead of simply salting, as with other meats. Some people prefer their chopped liver to be chunky rather than smooth, and so they either chop the mixture with a knife or grind it in a meat grinder. If you like it smooth, simply use a food processor. Serve the liver with any bread or cracker you like.
Traditional choices are rye bread, challah or, on Passover, matzoh.
Line the broiler rack with foil, adjust the rack 3 inches from the heat and preheat the broiler. Place the livers on the broiler rack, sprinkle with salt to taste and broil until lightly browned, about 3 minutes. Use a sharp knife to check. Heat the oil in a large skillet over medium-low heat. Add the onions and cook, stirring frequently, until tender and browned, about 15 minutes.