Wash the beets and cut off the greens about 3 inches from the bulb--do not peel! Boil them this way for about 30 to 45 minutes, or until just tender enough to slip off the skins; take the skins off, holding the beets under cold running water to do it. Cut the beets into julienne strips and put them in the broth, together with the strained mushroom stock. Season to taste with lemon juice and a little sugar--also salt, black pepper, and perhaps a few drops of vinegar. Simmer for about 10 to 15 minutes to bind flavors. Serve in large, shallow soup bowls; consider adding 4 to 5 hot dumplings to each bowl.