Rinse and drain barley. Place barley, water, chicken backs (or wings) and diced onions in a large pot over medium-high heat. Salt and pepper to taste. Cover the pot and bring to a boil, then reduce heat to medium and simmer for 30 minutes, stirring occasionally.
Add crushed tomatoes, chopped carrots, green onions and dried oregano leaves; cover and simmer until barley and carrots are tender and desired thickness (add more water during cooking if necessary), stirring occasionally. Then add butter and lemon juice. Take the chicken backs (or wings) out before serving.