And take to the streets. As Ettenberg recommended, street food (in addition to showcasing some of the world's best cooking) means meals prepared on the spot. Nothing that lingers all day, and ingredients that are added out in the open… just in case the chef reaches for that bowl of peanuts.
Finally, consider taking translation cards that lay this problem out in nuts, bolts and the local language.
Many countries, particularly in South Asia, often treat food allergies as a Western affectation. Cards, such as those offered by Ettenberg, hop the language and culture gap to explain exactly what's going on, and why a dash of fish sauce would be such a big deal.
Traveling with a chronic illness, such as diabetes or heart disease, adds a whole new level of complication to this issue. Although a personal illness involves fewer people than talking to every chef, it's no less a challenge to solve.
It is, however, a solvable one. As Menash Michael, the founder of Insulog and a diabetes patient for over 30 years, explained, illness doesn't have to stop people from taking their big adventures.
It just forces planning.
"You've got to be prepared for anything," he said. "Life is like that. You never know what's going to happen, but when you are traveling you're more in the places that you never know what to expect."
Take health insurance, for example. Ordinarily something that few vacationers worry about over a ten-day trip, this is something that travelers with a chronic condition should absolutely check on before heading out the door. The same holds for access to local doctors; not a concern for most people, diabetic travelers should absolutely look up where they would go for replacement insulin.