1 pound seedless cucumbers, thinly sliced crosswise on a mandoline
1 1/2 teaspoons sugar
1 1/2 teaspoons kosher salt
2 1/2 tablespoons red wine vinegar
1/2 small onion, thinly sliced
In a medium bowl, toss the cucumber slices with the sugar and salt and let stand for 5 minutes.
Stir in the vinegar and onion and refrigerate for 10 minutes, then serve.