3 tablespoons olive oil
3/4 pound russet potatoes, peeled, chopped
2 1/2 cups chopped green cabbage (about 1/4 of small head)
1 large onion, chopped
8 cups (or more) canned vegetable broth
6 2-inch-diameter beets, peeled, chopped
1 cup drained canned chopped tomatoes
1 tablespoon fresh lemon juice
Low-fat sour cream
Chopped fresh parsley
Heat oil in heavy large pot over medium-high heat. Add potatoes, cabbage and onion and sauté until cabbage softens, about 5 minutes. Add 8 cups broth, beets and tomatoes. Bring soup to boil. Reduce heat and simmer until vegetables are tender, about 30 minutes.
Working in small batches, puree 4 cups of soup in blender; return to remaining soup in pot. If desired, add more broth by 1/2 cupfuls to thin soup. Add lemon juice; season with salt and pepper.
Ladle soup into bowls. Top with dollop of sour cream; sprinkle with parsley. Serve, passing lemon wedges separately.