Beet and Cabbage Borscht

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. Enjoy hot or cold.