Fry the onions in olive oil until browned. Add the cinnamon and the bay leaf. Continue stirring and add the ginger, paprika, curry powder, sugar, salt and garlic. Continue stirring for 2 minutes. Mixture will become much like a paste.
Add chicken pieces and tomato. Add enough water to just cover the chicken. Simmer until chicken is done, about 20 minutes.
Just before serving, add the lemon juice and the cayenne pepper. Simmer for 5 more minutes.