How to Make It
Place apple cores and thyme sprigs in 1 (24-oz.) sterilized jar. Bring vinegar, sugar, and salt to a boil in a small saucepan over high heat. Pour vinegar mixture into jar, filling to 1/4 inch from top. Cool completely (about 30 minutes). Cover with lid, and chill 1 week before using. Refrigerate in covered jar up to 3 months.