Method
1 Remove greens from beets, save for future use (see beet greens recipe). Cut beets to uniform sizes so they will cook evenly. Steam or boil around 30 minutes or until done. (Alternatively, you can roast them by wrapping them whole in foil and cooking them in a 350°F oven for about an hour.) A fork easily inserted into the beet will tell you if the beets are done or not.
2 Drain the beets, rinsing them in cold water. Use your fingers to slip the peels off of the beets. The peels should come off easily. Discard the peels. Slice the beets.
3 Make the vinaigrette by combining the cider vinegar, sugar, olive oil, and dry mustard. Whisk ingredients together with a fork. The dry mustard will help to emulsify the vinaigrette. Adjust to taste. Add salt and pepper to taste. Combine beets and vinaigrette in a bowl and allow to marinate for a half hour at room temperature