"There's nothing better than a simple tempura of a primo vegetable," states Peter Hoffman. For this sensational version, he coats thick onion rings in an ultralight batter and quickly fries them. Hoffman says that any vegetable that slices nicely, like delicata squash, fennel or zucchini, would be great here, as long as it "takes to the batter"—meaning the batter stays on.
2 large Spanish onions, cut crosswise into 1/2-inch rings
2 teaspoons kosher salt, plus more for sprinkling
3 to 4 cups club soda, chilled
1 teaspoon baking powder
3 cups all-purpose flour
1/3 cup cornstarch
In a large bowl, whisk the flour with the cornstarch, baking powder and the 2 teaspoons of kosher salt. Whisk in 3 cups of the club soda until the batter is smooth. Add more club soda, about 1 tablespoon at a time, until the mixture is the consistency of thin pancake batter. Let stand for 10 minutes.
Meanwhile, in a large saucepan, heat the vegetable oil to 380°. Dip 8 onion rings in the batter, letting the excess drip back into the bowl. Fry the onion rings in the hot oil over high heat, turning occasionally, until golden and crispy, about 3 minutes. Transfer the onion rings to a paper towel-lined baking sheet and sprinkle lightly with salt. Repeat with the remaining onion rings and batter and serve hot or warm.