Saute onions, celery and apples in oil until slightly brown. Stir in curry powder and simmer 5 minutes. Add remaining seasonings and stock and cook 2 minutes. Stir in flour mixed with water and cook 5 minutes, stirring until thickened. Remove from heat and allow to stand one hour.
Reheat and add cooked meat, cream or milk, and egg yolk just before serving. Heat to boiling point, stirring constantly. Serve over rice