Tempura batter is a light and crispy coating used in Japanese cooking, primarily for frying vegetables and seafood. It is made from a simple mixture of flour, cold water, and sometimes egg. The key to achieving the perfect texture is to keep the batter cold and to mix it gently, avoiding over-mixing, which can lead to a dense coating. When fried, tempura batter creates a delicate, airy crust that enhances the flavor of the ingredients without overpowering them. This cooking method is popular in Japanese cuisine and is often served with a dipping sauce, making it a favorite dish in many restaurants around the world.