Tempura batter mix is made with a low gluten flour which helps keep the tempura light and crispy, as do two important techniques: First, the water used, the mixing bowl, even the chopsticks used to mix it, must be icy cold. Second, the batter must not be over mixed, which would activate the gluten; if there are no lumps of dry mix in the batter, it is over mixed. Items being fried are first lightly dusted in flour, then dipped in batter, then fried briefly – batter should colour only slightly. You could use a soft cake or pastry flour instead, but this tempura batter mix is raku raku, which means easy, and results will likely be better.