1. In a 6-quart saucepan, simmer lamb bones in 2 quarts of water and 2 teaspoons of salt (optional) for one hour.
2. Add onions, carrots, cabbage, string beans, and garlic.
3. Simmer for one hour until vegetables are thoroughly cooked.
4. Remove lamb bones and puree the mixture.
5. Add 4 Tablespoons peanut butter thinned with lemon juice.
6. Add cooked rice (optional).
7. Add salt and pepper to taste.
Shorba is a Sudanese dish based around lamb. In Sudan, lamb bones commonly are used to flavor the soup-like dish.