The flour-like starch of fresh water chestnuts makes a fine, super-white coating for deep-fried foods. The best brands are talc-like; we use King’s. Other brands are lumpy and require pulverizing in a food processor before use. This stuff is expensive, but the results are well worth it. One caution: water chestnut starch stays relatively white when cooked in fresh oil, so don’t wait for the golden tones of everyday flour or you will have overcooked your food.