Japan — 16th century adaptation of Portuguese battered vegetable technique; developed as a street food in Edo period; Kanda and Asakusa districts of Tokyo had famous tempura yatai street stalls; institutionalised as a high-end restaurant cuisine in the 20th century
Tempura's extraordinary lightness — the thin, transparent, barely-there batter that creates a gossamer-thin shell rather than a substantial coating — results from precise management of four factors: cold temperature throughout, minimal mixing, low protein flour, and high-temperature oil. Developed from Portuguese peixinhos da horta (battered vegetables) introduced to Japan in the 16th century and transformed into a completely distinct preparation, tempura's Japanese iteration abandoned the dense egg-heavy European batter and achieved a crystalline, shatteringly delicate shell unknown in any other frying tradition. The professional tempura batter is made with ice-cold water (sometimes with ice cubes floating in it), cold eggs, low-protein cake flour or a 50/50 cake/all-purpose blend, and is mixed with a light, almost careless cutting motion that leaves lumps deliberately in the batter.
Essentially neutral batter that acts as a translucent envelope revealing the ingredient inside; the texture — shatteringly crisp exterior giving to the tender interior — is the sensory focus; tsuyu dipping sauce adds the umami and seasoning dimension
The enemy of tempura is gluten development — any kneading or vigorous mixing creates gluten networks in the flour that produce a chewy, elastic batter rather than the desired glassy, light shell. Mix with a few quick strokes using chopsticks or a fork; visible dry flour and lumps are intentional. Oil temperature: 170–180°C for vegetables and small items; 180–190°C for larger prawns and thick items. Test oil temperature by dropping in a small amount of batter — it should sink slightly then immediately rise and spread without browning (180°C). The batter must be cold — warm batter doesn't create the correct steam explosion that forms the shell.
Professional tempura chefs keep the batter bowl inside a larger bowl of ice water to maintain the cold throughout service. Fresh, immediate service is critical — tempura degrades rapidly after frying. The professional tempura sequence at a restaurant counter: one piece per frying cycle, served immediately to the guest. Tendon (tempura on rice) is the home version — arrange freshly fried pieces over rice and pour tsuyu sauce (dashi-soy-mirin reduction) over everything just before eating. For kaki-age (mixed vegetable tempura fritter): mix the vegetables into a small amount of batter and drop as a cohesive mass, which fries as a unified crispy cake.
Over-mixing the batter — the most common error; lumps are correct. Using room-temperature or warm water — ice-cold water is non-negotiable. Using high-protein bread flour or all-purpose flour without modification — too much gluten development. Crowding the frying vessel, which drops oil temperature below the critical range. Not draining on a wire rack — paper towels absorb steam and soften the crust.
Tsuji, Shizuo — Japanese Cooking: A Simple Art; tempura master documentation