Cook beef shank in a large soup pot over high heat until browned, about 3 minutes per side; add water, onion, carrots, celery, and bay leaf to the pot, bring to a simmer and cook until meat is tender and falling off the bone, about 4 hours. Strain broth and discard solids.
Combine beef broth, beets, and cabbage in a large soup pot; cook, stirring occasionally, until beets are tender, about 30 minutes. Reduce heat to low; add vinegar, salt, and black pepper.
Serve garnished with sour cream and dill."