A beef liver is very much larger than you probably want for household use, so they are always sold sliced crosswise. Liver is held particularly compatible with onions in just about all beef eating cultures, so it's not easy to find a recipe that doesn't include them. The photo specimen was 11 inches long, 5 inches wide and 1 inch thick, weighing 1 pound 5 ounces.
More on Beef Innards
Buying: Liver is still fairly common in meat markets, but most available in ethnic markets serving Eastern and Southern Europeans, Mexicans and Middle Easterners.
Prep: The way they're sold around here there isn't much to do except remove a little plumbing, slice and rinse well in salted water - unless you need to kosher them.
Cooking: Liver is usually cut into smallish pieces and cooking time is kept very short, as liver tends to toughen with longer cooking. This is, of course, impossible with Jewish recipes since the liver is already well overcooked by the koshering process (see below).
Koshering: If you are using liver in a Jewish recipe, this procedure is necessary to reproduce the authentic flavor of the dish. If you are Jewish and want to keep "sort of kosher", the basic procedure here should do fine, but if you're keeping a hard core kosher kitchen there are a lot more details and you should consult a paper by an authorized rabbi.. The main point is this: blood is forbidden for Jews, and liver is so saturated with blood koshering by salt is considered insufficient.