3/4 cup water
3/4 cup red wine vinegar
1/3 cup sugar
2 tablespoons kosher salt
1/2 teaspoon dried crushed red pepper
1 1/2 cups thinly sliced shallots
Bring water, vinegar, sugar, kosher salt, and dried crushed red pepper to a boil, whisking until sugar and salt are dissolved. Pour over shallots in a sterilized canning jar. Cool to room temperature. Cover and chill 1 hour.