Set the oven to 400 degrees F. Wrap the beets individually in foil and bake for 40-70 minutes, until beets are soft all the way through. Set aside to cool; then peel and dice. Toss the rhubarb with the sugar, spread over a foil-lined oven tray and roast for 10-12 minutes, until soft but not mushy. Set aside to cool. In a large bowl, whisk the vinegar, molasses, maple syrup, oil, allspice, salt, and pepper. Add the onion, set aside for a few minutes to soften, and then add the parsley and beets. Stir to combine, and just before serving, gently fold in the rhubarb, its juices, and the cheese.