Preheat oven to 375ºF. For filling: sauté Onions in butter for 3 minutes. Add Garlic and mushrooms; cook for 2 minutes. Add remaining filling ingredients. Add herbs to taste: salt, pepper, tarragon, fines herbs. Set aside. Pound chicken breasts till thin. Place one tablespoon filling on each breast. Roll and tie with cooking string. Dredge in seasoned flour. Chill for 30 minutes or overnight.
In skillet, brown roll-ups in butter for 5 minutes and place in casserole dish. For sauce: sauté Onions, Garlic, mushrooms, Celery and Carrots in butter. Add flour and cook until golden. Add white wine, chicken broth and Tomato paste, stirring until smooth. Add Thyme, bay leaves, salt and pepper to taste. Pour sauce over chicken roll-ups in casserole. Cook covered for 30 minutes. Serve with long grain and wild rice. Makes 8 roll-ups.