A family-run restaurant in Bangkok has had a the same giant pot of soup simmering for 45 years. When it runs low, they top it off. It’s a beef noodle soup called neua tuna. It simmers in a giant pot. Fresh meat like raw sliced beef, tripe and other organs is added daily. But any broth leftover is preserved at the end of each day and used in the next day’s soup. It’s an ancient cooking method that gives the soup a unique flavor and aroma.