Coat the chicken joins with flour. Heat the butter and oil in a large pan. Add the chicken joints and fry until crisp and golden. Remove to a plate.
Add the onion and garlic to the pan and fry gently until pale gold.
Stir i the tomato sauce, tomato concentrate, sugar and stock, then season well to taste with salt and pepper. Bring to a boil .
Replace the chicken, cover the pan and simmer slowly for 30 to 45 minutes. Add the mushrooms and wine and contineu to cook for a further 10 to 15 minutes.
