How do I make tempura turn out light?

Question

I've probably only made tempura 10 times in my life, with fairly inconsistent results. often it has been heavier than the best restaurant versions I've had. There seem to be many variables involved:

• type(s) of flour
• added pure starch (cornstarch, arrowroot, ...?)
• use of seltzer
• use of chemical leavening
• overall thickness of batter
• type of oil
• temperature of oil

Which of these factors (and any others I've forgotten) are most important to getting a thin, light, non-greasy tempura shell?

Answer 1

Type of flour: rice Liquid: soda (seltzer) water

Mix as little as possible. Lumps are okay. Dip quickly, drop into 350 veg/soy oil.

Answer 2

In addition to what Roux suggests, I find it helps to keep the batter really cold while you're mixing and using it. I tend to keep the bowl of batter in a bowl of ice water while I'm using it.