Preheat oven to 400F. Wrap sets of 2 beets each in sheets of foil. Bake on a baking sheet for 1 hour or until tender. When cool enough to handle, rub off skins under running water.
Meanwhile, whisk together vinegar, honey, horseradish, mustard, salt and pepper in a medium bowl; pour over beets. Toss with 2 tablespoons of chives. To serve, spoon over watercress and top with remaining chives.
Try a crisp, assertive white wine, like the German Dr. M. Prüm Riesling ($12) for a perfect balance of sweet and tart autumn fruits or New York State's award-winning Dr. Konstantin Frank's Johannisberg Riesling ($11). For a red, try Domaine de Piaugier Sablet ($10), an earthy wine with pepper-spice overtones.