As Bangkok rises into the ranks of the world’s great culinary destination cities, its restaurant scene caters to ever more well-heeled travelers. There, you can now visit establishments with not just one, and not just two, but three Michelin stars. Even so, many a Bangkok habitué will surely tell you that the city’s best food is still served in the same humble places as always, or at least whose rent hasn’t been hiked too badly. Even in as hipsterized an area as Ekkamai Road, though, some have been around long enough to own their real estate. Take Wattana Panich, which has been serving beef noodle soup in its own building for more than 50 years — and indeed, using the same broth the whole time.You can have a look at the process in the Great Big Story video at the top of the post. “Forever soup, also known as perpetual stew or hunter’s pot, is enjoying a moment as adventurous cooks and intrepid diners rediscover the old method in which a broth can simmer for weeks, months or even years,” writes Shan Li in a recent Wall Street Journal article.Third-generation Wattana Panich owner Nattapong Kaweenuntawong “has tended the broth from morning until night since gaining custody two decades ago. By day, it bubbles in a giant stainless-steel pot about 5 feet across and one foot deep, encased in lava-like concrete and heated by gas. He tweaks the flavor by adding fresh ingredients, including fish sauce, soy sauce, chunks of beef and sachets of Chinese herbs.”Perhaps you feel you can taste it already. But its regular visitors may insist that you’ll never really know the flavor of the shop’s eponymous broth, continuously refined while being rolled over night after night for five decades, until you try it for yourself. The prospect may put certain Westerners, uncomfortable consuming even last night’s leftovers, ill at ease. But they should rest assured that the solid ingredients are always fresh. It’s just the broth itself, rigorously strained each night and boiled each day, that has been kept in use, tying the establishment to its own past in the same manner as its inherited ownership. As with any family business, of course, each generation gets completely displaced sooner or later, just as every molecule of “forever soup” at one time will, in theory, have been consumed by some later time. Is the broth Wattana Panich uses today really identical to the one it started with in 1974? That’s a philosophical question best saved for after the meal.Related Content:Chowda!: Three Centuries of Recipes Reveal the Rise of New England’s Finest Culinary ExportWhen Al Capone Opened a Soup Kitchen During the Great Depression: Another Side of the Legendary Mobster’s OperationAllen Ginsberg’s Personal Recipe for Cold Summer BorschtHow to Make the Oldest Recipe in the World: A Recipe for Nettle Pudding Dating Back 6,000 BCThe Oldest Restaurant in the World: How Madrid’s Sobrino de Botín Has Kept the Oven Hot Since 1725Based in Seoul, Colin Marshall writes and broadcasts on cities, language, and culture. He’s the author of the newsletter Books on Cities as well as the books 한국 요약 금지 (No Summarizing Korea) and Korean Newtro. Follow him on the social network formerly known as Twitter at @colinmarshall.