In the same saucepan, bring the vinegar, sugar, and salt to a boil. Simmer over low heat for about 10 minutes. Add the beets and bring to a boil, stirring frequently. Add the gelatin and cook for 1 minute, stirring until dissolved. Spoon into jars. The candied beets will keep for about 3 weeks in the refrigerator or can be frozen or offered as a gift.