Moscatel vinegar made by the Spanish brand Unió is Sharon Adriana's (Ragazza, Gialina) favorite for dressings and adds a complex, fruity note. It's available at Whole Foods, at San Francisco's Rainbow Grocery in the bulk section, and at many specialty stores. If you can't find it, use Champagne vinegar.
Taylor's Market in Sacramento sells it online at:
The Russian Tea Room is once again in business and their borscht recipe (different from the earlier era Russian Tea Room recipe cited above) is online here (including a video):
This looks fairly easy and would be interesting to try as well modified with the brisket mentioned in a recipe above. (Since it's so simple, it ought to be stellar with homemade stock, but I'm sure it's good with commercial stock too -- it's borscht, it's hard to go wrong with it.)
1. Place the bacon in a Dutch oven or stockpot and cook over medium-high heat until the fat begins to render, about three minutes.