875g/1lb 15oz button mushrooms
5 onions, sliced
small bunch curly parsley, finely chopped
25g/1oz fresh tarragon, half left as sprigs, half finely chopped
2.8 litres/5 pints chicken stock
5 x 400g/14oz tins chopped tomatoes
125驳/4陆辞锄 plain flour
150ml/5fl oz sunflower oil
150ml/5fl oz tomato pur茅e
7.5kg /9lb 13oz chicken thighs, skinned and bone removed and cut into 3cm pieces