Preheat the oven to 375ºF (190ºC). Wrap the beets in tin foil and roast for 35 minutes.
In a large bowl, thoroughly toss the onions, apples, garlic, carrots, and bay leaves in the vegetable oil. Wrap tossed vegetables in tin foil, and place in the oven with the beets and roast for another 45 minutes.
Remove the beets from the oven, cool slightly, and peel (the peel should slip off quite easily). Cut into chunks. Discard the bay leaves and place half of all the roasted vegetables, as well as half the vinegar and 2 cups (475 mL) of stock in a blender or food processor. Purée until smooth. Repeat with the rest of the vegetables and vinegar and another 2 cups (475 mL) of stock. If the soup is too thick, pour in a bit more stock. Season with salt and pepper to taste and serve, heated, in individual bowls topped with crème fraîche.
For Crème Fraîche
Whisk the cream and buttermilk together in a wide-mouthed bowl. Cover with a towel and leave at room temperature until it becomes as thick as softly whipped cream, about 12 to 24 hours. Cover with plastic wrap and refrigerate until ready to use. Crème fraîche will keep in the refrigerator for 5 to 7 days.
Photo by Doug Bradshaw.