This recipe is from Craig Claibourne's New York Times Cookbook, and I think it's one of the best recipes I've ever tried. It looks beautiful, I love the flavors, and in my opinion, well worth the work. Don't leave out or substitute for the whole bottle of lemon extract added at the very last second; it's what makes the dish. If you cannot find water chestnut flour or powder, you can substitute cornstarch. However, the texture will not be as crispy or nutty.