A light batter is made of cold water (sometimes sparkling water is used to keep the batter light) and soft wheat flour (cake, pastry or all-purpose 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. Overmixing the batter will result in activation of wheat gluten, which causes the flour mixture to become chewy and dough-like when fried.
Specially formulated tempura flour is available in worldwide supermarkets. This is generally light (low-gluten) flour, and occasionally contains leaveners such as baking powder.
Tempura generally does not use breadcrumbs (panko) in the coating. Generally, fried foods which are coated with breadcrumbs are considered to be furai, Japanese-invented Western-style deep fried foods, such as tonkatsu or ebi furai (fried prawn).