is a classic Japanese dish of deep fried battered vegetables or seafood.
Preparation
Batter and Frying
A light batter is made of cold water and wheat flour. Eggs, baking soda or baking powder, starch, oil, and/or spices may also be added. Tempura batter is traditionally mixed in small batches using chopsticks for only a few seconds, leaving lumps in the mixture that, along with the cold batter temperature, result in the unique fluffy and crisp tempura structure when cooked. The batter is often kept cold by adding ice, or by placing the bowl inside a larger bowl with ice in it. Over-mixing the batter will result in production of wheat gluten, which causes the flour mixture to become chewy and dough-like when fried.Specially formulated tempura flour is available in Japanese supermarkets. This is generally light (low-gluten) flour and occasionally contains leaveners such as baking powder.Some varieties of tempura are dipped in a final coating, such as sesame seeds, before frying
Source:
http://en.wikipedia.org/wiki/Tempura