Many years ago I saw a Japanese TV program that explored the food of southern Taiwan and one of the stops was a restaurant that had a 106-year old vat of broth. It was tall and narrow and had a giant hump of crust on one side.

If it's still open, it would be going for 130+ years at this point.

ETA: Found it. Established 1895, the year Taiwan was annexed by Japan. It's not soup, it's a meat sauce (滷肉) used on a noodle dish. Scroll down to the middle of the page, which shows the chef with the pot in front of him.

https://ksdelicacy.pixnet.net/blog/posts/5067270713

I think there is an optimization question buried here. In tech lots of people have experience with A/B tests, which function on the assumption that you have a stream of fresh sessions which are independent. Multi-armed bandits, Thompson sampling etc give us frameworks for generalizing this towards finding the best option among a finite set of candidates, if goodness is fixed over time. This is kinda the opposite end of a spectrum: you get to run one policy at a time and the whole premise is that goodness is heavily state dependent. How do you decide whether to keep going with your current policy vs when to start over with another?

Sure, the soup is good ... but is it the best they could have after 52 years? By committing to maintaining one pot for so long, they pay the opportunity cost of not being able to explore related long-lived methods. If there's a different recipe that surpasses this one after only one year of simmering, they'll never find it.

At first I thought this might be related to the secretary problem, but of course if after 50 years of recipe B, you have the option of switching back to recipe A if it's better.

Wouldn't toxics like nitrites accumulate over the years? Also, I'd assume the purpose of perpetual soup is to concentrate the aroma and the taste, but is there going to be a diminishing return?

Perpetual stew: https://en.wikipedia.org/wiki/Perpetual_stew

I've gone without a fridge for 8 years now and do something kind of like this usually - I'll cook a pot of food and then steam or boil it again after ~24 hours to reset the clock on it rotting. It's handy for things like eating a whole chicken or other large soup. I switch between being home and on the road a lot so my pot just comes with me and can be re-cooked on my car stove or my home stove. I tend to cook or re-heat once a day. Ideally I'd rather be sharing freshly prepared food with other people every meal and I do that when I can, but this works for when I'm feeding myself alone - cheaper and easier than any other approach.

One of the speculations as to how life was created on this planet: stable environments hosting hydrothermal vents over long periods of time.

Could perpetual stews over decades act in the same manner?

Forever soup isn't new, of course.

Poor families do it to cheaply make long lasting meals.

My late maternal grandmother used to have a pot of forever soup on the stove, and she would put whatever she had on hand in.

Spare ribs, check. Leftover veg, check. McDonalds fries, gross, but check.

I'm currently in bangkok atm. where can I go try this soup?