Do you like to eat leftovers? At Wattana Panich bistro in Bangkok, you can have a bowl of soup that's been in the pot for almost 50 years. Known as neua tune, it follows the "perpetual stew" method of preparation: the leftovers at the end of each day are kept overnight to become the base for the next day's soup.
Cultures all across the world have versions of perpetual stew. In France, it's called pot-au-feu, or "pot in the fire", for the way it was traditionally cooked—in a pot that hung over the hearth fire all day. Other cultures' versions of perpetual stew include Chinese master stock, Mongolian Firepot, and Olla Podrida (literally, "rotten pot") in Spain. In the U.S., we have "hunter's stew", and the wonderfully named "Skilligalee" of pioneer times.
Modern home cooks use slow cookers—electric pots that you can start in the morning and leave on low all day (or overnight)—to make big batches of soups and stews. Then you can eat the leftovers for the next day or two, or four...