Heat the oven to 400°F. Wash the beets well. While they are still wet, wrap each one in foil and put them on a baking sheet or in a roasting pan. (Alternatively, don’t wrap them but bake them in a covered casserole or roasting pan.) Bake the beets, undisturbed, until a thin-bladed knife pierces all of them with little resistance, 1 to 1 ½ hours. (They may cook at different rates; remove each one when it is done.)
Meanwhile, whisk together the oils, vinegar, soy sauce, peanuts, and scal- lions in a large bowl; sprinkle with pepper. Once the beets are cool enough to handle, peel off their skins, cut them into wedges or cubes, and combine them with the dressing in the bowl. Taste and adjust the seasoning, adding a little salt if necessary. Serve at room temperature (or refrigerate for up to 4 hours and return to room temperature before serving).
