Heat oil in stockpot, add onion, garlic, and saute for 5 minutes. Add the kidney beans and cayenne pepper, saute for 1 minute then add broth. Bring to a boil, reduce the heat, cover and simmer for 1 hour until beans start to break down. Add the diced chicken, return to a boil and simmer for several minutes, lower the heat and add rice and tomatoes. Continue cooking until chicken is tender. Remove from heat, remove bay leaf, garnish and serve.