1 Pound red beets
1/4 Cup extra virgin olive oil
3 Tablespoons prepared mustard, preferably whole grain or Dijon
1 Medium onion, chopped
Salt to taste
3 Tablespoons red wine vinegar
Instructions
Cut the tops off the beets, leaving 1� of stems attached. Place the beets in a pot of cold water to cover, bring to a boil, reduce heat, and boil until the beets can easily be pierced through with a sharp knife, 45-60 minutes depending on their size.
Meanwhile, put the mustard in a bowl and whisk in the vinegar. Then whisk in the olive oil in a steady stream until the sauce is smooth and creamy. Add the onions.
When the beets are done, drain them, and submerge them in several changes of cold water until they are just cool enough to handle. Cut off the roots and tops, slip the skins off, and slice the warm beets into the mustard sauce. Mix well, cover, and let marinate in the refrigerator for at least 24 hours. Before serving, mix well and add salt if desired.