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It's often called the 'ketchup' of Vietnam because they seem to put it on everything, but Nuoc Mam, or fish sauce, is far from the ubiquitous American condiment.

Simply put, it is the liquid drained from salted, fermented fish. A cook can then jazz it up using lime juice, garlic, chili pepper, or other 'secret' ingredients.

This woman sells her homemade brew in 5 different qualities - depending on how long it's been aged. We sprung for the good stuff - at about a buck a liter.