When buying sea scallops, pick the firmest, freshest available, and use as soon as possible (after removing the little hard white side muscle with a sharp knife).
Heat oven to 400 degrees.
Wrap the red beets in a foil packet and roast for 1 1/2 hours, or until soft. Boil the baby golden beets in salted water for 10 minutes, and cool immediately in ice water. Peel the beets and cut into thin disks; put red beets in a shallow bowl with 4 tablespoons rice-wine vinegar and yellow beets in a separate bowl with 1 tablespoon vinegar and 2 tablespoons water.
Heat 1 tablespoon peanut oil in a large saute pan. Lightly flour the scallops. Saute them over high heat until browned, about 4 to 6 minutes. Do not crowd the scallops--saute them in 2 or 3 batches. (Use another tablespoon of peanut oil for each additional batch.) When golden brown, turn them and cook 2 minutes more; then set aside in a warm oven (250 degrees).
When all the scallops are sauteed, pour off any remaining oil. Add the red and golden beets and cook for 30 seconds over high heat. Add the spinach, orache, remaining 2 1/2 tablespoons of vinegar, ginger, garlic, and sesame oil. Turn the spinach until slightly softened. Serve immediately, topped with the scallops.