Heat oil to 370 degrees in a wok or large pot. In a medium bowl, set over
an ice bath, stir yolk with chopsticks or a whisk, add water, stirring to
combine. Sift flour and cornstarch into egg mixture, stirring to
incorporate. Don't worry about the few remaining lumps in the batter. Coat
onion rings with batter, letting excess drip back into bowl. Fry onion
rings, turning once, in small batches in the oil until just beginning to
color. Drain on paper towel. Repeat process; skimming oil of tempura batter
bits as necessary, until all onion rings have been fried. If oil becomes
dark, begin again with fresh oil. Serve immediately. Makes 4 servings.
Comments: When Martha visited Tokyo years ago, Ten Masa, a tempura master,
shared with her a few golden rules. When making batter, use ice water, cake
flour, cornstarch and egg yolks. Always cook in fresh cottonseed oil; skim
frequently for bits of cooked batter; and be sure to change the oil when it
becomes discolored. Time is of the essence when making and serving tempura
onion rings. The batter should be prepared just before cooking and should
be ice cold so that when the batter-coated food hits the hot oil, it seals
quickly, and the food is cooked instantly. Since tempura waits for no one,
serve it immediately. A small basket or plate lined with a folded piece of
special absorbent paper known as shiki-shi is the traditional manner of
serving tempura. Accompany tempura onion rings with a dipping sauce of soy,
wasabi and grated daikon or follow the decidedly American route of pairing
the onion rings with a hamburger and ketchup.