The recipe we used called for cider and sherry vinegars, vermouth, salt and sugar, as well as peppercorns, mustard seed, chile, and rosemary for flavor. The result was a satisfyingly crunchy onion, very salty-tasting when sampled on its own, but just right when paired with gin or vodka. We were concerned that the caramel-coloring from the flavored vinegars would cloud our otherwise crystal-clear drink, but it blended in just fine.
yields 30-40 onions
1 pound pearl onions
1/2 cup sherry vinegar (white vinegar may be substituted)
1/2 cup apple cider vinegar
1/2 cup water
1/2 cup kosher salt
1/4 cup sugar
1/2 teaspoon whole mustard seed
12 whole peppercorns
1 sprig rosemary
1 dried chile pepper
1 cup dry (white) vermouth
Peel the onions by placing them in a large bowl and adding enough boiling water to cover. Leave to stand for one minute, then drain and rinse in cold water. Trim the root and top ends of the onions with a sharp knife. The outer skins should now slip off easily.
Combine all the remaining ingredients (except the vermouth) in a medium saucepan, and bring to a boil, stirring until the sugar and salt are dissolved. Add onions, reduce heat, and simmer for two minutes. Remove the pan from the heat and allow the mixture to cool. Stir in the vermouth. Transfer the onions and liquid into a tightly-covered jar and chill in the refrigerator. The onions will be ready to be consumed in 4-5 hours, and will keep in the refrigerator for up to a month.