Preserved radish substitutes

The bright yellow crunchy daikon pickle sold in vacuum packs in Japanese and Korean groceries. Rinse it well, dice it small, and blot it dry before it goes in the pan.

Best for

pad thai, fried rice, omelettes, noodle dishes, congee

The best widely available match, because it is the same vegetable preserved to a similar chewy-crunchy texture. The difference is that takuan is pickled in vinegar or rice bran and is distinctly sour, where sweet chai po is caramel-sweet and salty, so a pad thai made with it tastes tangier. Rinsing removes much of that, and tossing the dice with a quarter teaspoon of sugar per two tablespoons closes most of the remaining gap.

The knobbly salted mustard stem sold in pouches and cans at Chinese groceries, often already shredded. Rinse thoroughly under cold water and squeeze dry.

Best for

fried rice, noodle dishes, congee, stir-fries, pad thai

Texture is excellent, dense and crunchy exactly like chai po, and it delivers the same jolt of concentrated salt. The differences are chili and mustard: most zha cai is coated in chili paste and has a distinct mustardy sharpness, so the dish gains a low hum of heat and a peppery edge. Rinse hard to get the chili off, and cut the salt elsewhere in the recipe.

Salted and often sour-fermented mustard greens, sold in bags, cans or loose. Rinse, squeeze dry and chop finely.

Best for

noodle soups, stir-fries, fried rice, khao soi, braises

Very close on the savoury-salty job and easy to find, but the texture is softer and more leafy than the leathery chew of preserved radish, so it disappears into the dish rather than turning up as distinct little nuggets. Sour-fermented versions add a pleasant tang. A good swap in anything wet, a weaker one in pad thai where the bite matters.

Dice fresh daikon or white turnip very small, then fry in a teaspoon of oil over medium heat with the sugar and salt for 5 to 7 minutes until the edges brown and the pieces turn chewy and translucent.

Best for

pad thai, fried rice, omelettes

The best from-scratch approximation and the reason is chemistry: browning plus salt and sugar produces the same sweet-savoury caramelised note that curing and sun-drying give chai po. What it will not produce is the leathery, concentrated chew that months of drying create, so the pieces stay softer and more vegetal. Still much better than leaving the ingredient out entirely.

A Western-pantry fallback. Rinse well, squeeze out as much liquid as you can, chop very finely, and fry briefly in oil with a pinch of sugar to drive off moisture.

Best for

pad thai in an emergency, fried rice, omelettes

This is the honest least-bad option and it does not hide. The crunch and the salt are in the right place, but vinegar and dill or caraway are not Thai flavours, so the dish picks up a sour, pickled note that a Thai cook would immediately notice. Fry it hard to cook off the vinegar, add a pinch of sugar, and use half as much as the recipe asks for.

If you have none of the above, do not just delete the ingredient. Nudge up the two seasonings that carried the same flavours, so the sauce still lands sweet and salty.

Best for

pad thai, noodle dishes, fried rice

You are replacing the seasoning function and accepting the loss of texture, which is the correct trade-off when you have nothing suitable. The pad thai will taste right and lack only those occasional sweet-salty crunchy nuggets. Nobody who has not eaten the ingredient before will know what is missing.