Cornstarch (玉米淀粉)
Cornstarch (also called corn flour in the UK, or 生粉/玉米淀粉 in Chinese) is one of the most versatile ingredients in Chinese cooking. It serves three completely different functions: thickening sauces into glossy, clingy coatings (勾芡); velveting meat to keep it tender during high-heat cooking (上浆); and coating proteins for deep-frying to achieve a shatteringly crispy crust (裹粉). Each use has a different ideal substitute because the physics involved are different — thickening is about starch gel formation, velveting is about surface protection, and frying is about dehydration and crisping. Finding a single perfect substitute for all three is difficult, but individual replacements work well within their specific role.
Potato Starch (太白粉/马铃薯淀粉)
Ratio
1:1 by volume for all three uses (thickening, velveting, coating)
Flavor Change
Potato starch produces a glossier, more transparent sauce than cornstarch — the finish looks more 'restaurant quality.' For velveting, the texture is nearly identical. For frying, potato starch creates a lighter, more delicate crust that stays crispy slightly longer than cornstarch. The flavor difference is essentially zero.
How to Compensate
No compensation needed — potato starch is the closest functional match and is arguably superior for certain applications. One note: potato starch sauces can thin out if held at high heat for too long (they 'break' more easily than cornstarch). Add the slurry at the end and serve quickly. For frying coatings, use it exactly as you would cornstarch.
Tapioca Starch (木薯淀粉/太白粉)
Ratio
1:1 by volume for thickening and coating; 1:1 for velveting
Flavor Change
Tapioca starch creates a slightly chewy, elastic texture in sauces — think bubble tea boba, which is made from tapioca. The sauce will be glossy and clear but with a subtle bouncy quality that cornstarch doesn't produce. For frying, tapioca creates a crunchier, chewier crust — excellent for Taiwanese-style popcorn chicken. For velveting, it works well but the meat surface may feel slightly stickier before cooking.
How to Compensate
For sauces: use the same amount but stir continuously as it thickens — tapioca starch can clump more easily than cornstarch. For frying: tapioca actually outperforms cornstarch for extra-crispy applications. For velveting: works identically, no adjustment needed.
All-Purpose Flour (中筋面粉)
Ratio
2 tablespoons flour per 1 tablespoon cornstarch (for thickening); 1:1 for coating (but different result)
Flavor Change
Flour contains gluten and protein in addition to starch, which changes the result significantly. For thickening: sauces will be opaque and matte instead of glossy and clear. The texture is heavier, more like gravy than the light, silky sheen of a Chinese stir-fry sauce. For frying: flour creates a thicker, breadier crust (think KFC-style) rather than the thin, shattering shell that starch produces. For velveting: flour works in a pinch but the coating is heavier and more visible on the meat.
How to Compensate
For thickening: use twice the amount and cook the sauce for an extra 2 minutes to eliminate the raw flour taste (starch doesn't have this issue). Sauce will never be glossy — accept the trade-off. For frying: mix flour 50/50 with any starch you have (even potato or tapioca) for a better result than flour alone. For velveting: it's the weakest substitution. If you only have flour, reduce the amount by 25% so the coating isn't too thick.
Where to Buy
Cornstarch is available everywhere — any supermarket carries it (Argo and Kingsford's are the most common US brands). In Asian grocery stores, look for boxes or bags labeled 玉米淀粉 or 生粉. In the UK, 'cornflour' is the same product. For bulk purchases, Amazon carries 1-2 lb bags for under $5. Note: 'corn meal' and 'corn flour' (US usage, meaning finely ground whole corn) are NOT the same as cornstarch — make sure the ingredient list says only 'cornstarch' or 'corn starch.'
FAQ
What is the difference between cornstarch, potato starch, and tapioca starch for Chinese cooking?
All three are pure starches with no gluten, but they behave slightly differently. Cornstarch: most common, produces a semi-glossy sauce, good all-rounder. Potato starch: glossier finish, slightly more transparent, breaks down if overheated. Tapioca starch: chewier texture, best for crispy coatings, slightly elastic sauces. For everyday Chinese cooking, any of the three works. Many Chinese home cooks actually prefer potato starch (太白粉) for its glossier sauce finish.
Why do Chinese recipes call for cornstarch slurry instead of just adding cornstarch directly?
If you sprinkle dry cornstarch into a hot sauce, it clumps instantly — the outer surface gelatinizes and seals water out, creating lumps that never dissolve. Mixing cornstarch with cold water first (a 'slurry,' typically 1:2 ratio of starch to water) separates the granules so they disperse evenly when added to the hot sauce. Always stir the slurry right before adding — starch settles to the bottom in seconds.
How much cornstarch do I need to thicken a Chinese sauce?
A general rule: 1 tablespoon cornstarch mixed with 2 tablespoons water will thicken about 1 cup (240ml) of liquid into a light, clingy sauce. For a thicker, more viscous sauce (like the glaze on General Tso's chicken), use 1.5-2 tablespoons per cup. Start with less — you can always add more slurry, but you can't un-thicken a sauce.