Coat chicken pieces with flour. Brown well in butter and oil in a large skillet. Add onion, green pepper, celery, carrots, and mushrooms. Cook for 2 minutes; add tomatoes, salt, paprika, and pepper. Cover and simmer for 1 hour, until chicken is tender. Remove chicken, reserving liquid; keep warm while making gravy. Skim excess fat off liquid in skillet. Combine 1/4 cup flour with the sour cream; whisk or beat until smooth. Stir into the liquid and cook over low heat 3 to 5 minutes, until heated through and smooth.
Chicken recipe serves 6.