Combine beans and stock in a large pot. Bring to a boil and simmer for 15 minutes. In frying pan, saute onions in oil for 10 minutes. Add to beans and simmer for 30 minutes. Add kielbasa and tomatoes, bring to a boil and simmer for 15 minutes. Add broccoli rape to the soup, along with red pepper, salt and pepper. Simmer for 5 minutes and serve.