Season chicken with salt and pepper. Brown pieces in olive oil, transferring them to a plate as they brown. Add onions to the pan and cook until soft. Add garlic and mushrooms. Add vinegar cook until it evaporates. Add wine and cook until almost evaporated. Add chopped green pepper and tomato to the onions amd simmer covered until it becomes a paste. Return chicken pieces to the pan .Bring to a boil. Cover pan and simmer 45 minutes or untilchicken is cooked through. Let cool. Remove meat from bones and cut into bite size pieces. Return chicken to sauce. Add olives, bring to a boil.
Chill before using.