Seven years ago I was in Hanoi on assignment for Saveur magazine. My task was to explore Hanoi-style pho for a column called “Classics.” I’d done lots of reading and research and knew about ingredients like peanut worms (sa sung), which are used for umami in pho. I arrived in the capital thinking I’d be talking to local chefs about the worms, which seemed strangely and unique to the northern pho experience. But what I didn’t expect to encounter during my Hanoi pho experiences was dam toi garlic vinegar. Just like the above photo show, the vinegar appeared in plastic containers with long spoons for people to help themselves. It was on tables at nearly every pho shop I visited. It's what Hanoians expected