Soy Sauce with Lime Juice (Best Option)
1 tablespoon soy sauce + 1 teaspoon lime juice per 1 tablespoon fish sauceSoy sauce provides a salty, umami-rich base similar to fish sauce, while lime juice adds the necessary acidity to mimic the tangy brightness of fish sauce. This combination maintains the dough's yeast fermentation and gluten development without introducing unwanted moisture or overpowering flavors.
When mixing, add the lime juice last to prevent soy sauce from becoming too salty or bitter. Use light soy sauce if possible to avoid darkening the dough excessively. Monitor dough hydration as small adjustments might be needed.
Compared to fish sauce, this substitute yields a slightly less complex umami but retains the essential savory and acidic notes, resulting in a traditional bagel texture and flavor that is close to the original.