With lacy, crisp, melt-in-your-mouth golden batter enrobing shrimp or vegetables, tempura-style fried food is a delectable treat. Some Japanese chefs even devote their entire careers to this one technique.
The tempura template is deviously simple: Stir together a batter of egg and equal parts flour and ice water; dip in pieces of food; drop into hot oil; and fry. But success hinges on this batter, which easily turns thick and heavy from being overmixed or left to sit for too long, resulting in fried food that’s greasy and doughy, more the stuff of a county fair than a restaurant.
Tempura-style batter is persnickety because of its gluten. When water and flour are mixed, the proteins in flour form gluten. Protein from the egg buttresses the gluten structure. As it hits the hot oil, the water in the batter rapidly expands into steam, creating small bubbles. At the same time, the egg and gluten coagulate and stiffen, strengthening those bubbles. This chain of reactions is what gives tempura-style crusts their intricate, lacy-crisp texture. But when the batter sits for any length of time, it quickly turns tough, because gluten develops even without stirring.
To significantly improve tempura batter’s lightness, replace part of the flour with cornstarch, which does not develop gluten. Cornstarch also contributes to great crispness by increasing the batter’s starch content. Switching from tap water to effervescent seltzer water lightens the batter further, because its bubbles provide lift as they escape during frying, making the coating even lacier. And the carbonation makes the batter slightly more acidic, limiting how much gluten can form.
But the ace in the hole for ethereally light fried food can be found in the liquor cabinet. The test kitchen has used vodka to minimize the effects of gluten in pie dough, since the alcohol in vodka inhibits gluten
development by limiting the amount of water that’s available to the flour. Substituting vodka for a portion of the water solves the problem of batter that toughens as it sits in an unconventional but very effective way. Because vodka is about 60 percent water and 40 percent alcohol, it makes the batter fluid and keeps gluten formation in check no matter how much you stir the batter or allow it to sit.
1 Heat oil to correct temperature in Dutch oven.
2 Whisk flour and cornstarch in bowl. Whisk egg and vodka in second bowl. Whisk seltzer water into egg mixture.
3 When oil has almost reached correct temperature, gently whisk seltzer mixture into flour mixture (it’s OK if small lumps remain).
4 Working in batches, dip food into batter. Remove from batter, allowing excess to drip back into bowl, and transfer to hot oil.
5 Using slotted spoon or spider, transfer fried food to paper towels to drain. Serve immediately.