Trim the top of a head of garlic to expose the cloves and drizzle on vegetable oil. Roast a head of garlic in aluminum foil at 400°F for 30 to 45 minutes
Trim and wash beets. Steam for 15 minutes at High Pressure using 2 cups of water. Do a quick release of the steam.
While the beets are steaming, saute the chopped onion with 1 Tablespoon butter and 1 Tablespoon vegetable oil (or 3 Tablespoons vegetable oil). Cook slowly in a frying pan on medium-low heat for 15 minutes
Chop the mushrooms and add to the onions. Increase the heat to medium and cook for 7-8 minutes.
Add the chopped roasted garlic cloves and beets. Combine with 1 Tablespoon sugar and 2 Tablespoons of apple cider vinegar. Refrigerate overnight or for at least 2 hours. Serve cold or at room temperature.
Notes
This is a great recipe to make 1 or 2 days ahead. It does not freeze well.