Soy Sauce (Best Option)
1 teaspoon soy sauce per 1 teaspoon fish sauceSoy sauce works well as a substitute because it contains glutamates that provide umami, similar to fish sauce. Its saltiness helps balance sweetness in muffins without adding fishy notes.
When using soy sauce, choose a light or low-sodium variety to prevent overpowering the batter or altering the color significantly. Mix it thoroughly to ensure even distribution.
Compared to fish sauce, soy sauce is less pungent and fishy, resulting in a milder umami background that complements rather than dominates the muffin's flavor profile.