- 2 cups finely chopped cucumber (about 3 Kirby cucumbers)
- 1/2 cup finely chopped onion
- 1/2 cup distilled white vinegar
- 1/4 cup sugar
- 1 teaspoon cornstarch dissolved in 1 teaspoon water
- Toss cucumber and onion with 3/4 teaspoon salt in a sieve set over a bowl and drain 3 hours. Discard liquid from bowl. Wrap cucumber and onion in a kitchen towel (not terry cloth) and squeeze out as much liquid as possible.
- Bring vinegar, sugar, and 1/4 teaspoon salt to a boil in a small heavy saucepan, stirring until sugar has dissolved, then boil until reduced to about 1/2 cup, 3 to 4 minutes. Add cucumber-onion mixture and simmer, stirring, 2 minutes. Stir cornstarch mixture, then stir into relish. Simmer, stirring, 1 minute. Transfer relish to a bowl and chill, uncovered, until cold, about 1 1/2 hours.