I use chicken legs, and get the butcher to cut each one in half so you get a thigh and a drumstick.
Put the oven on to about 190 degrees C.
Wash the chicken in a colander, and cover in cornflour or plain flour, seasoned with pepper (and salt if you like). Heat some oil or butter in a frying pan and brown the chicken quickly on all sides. Remove the chicken into a casserole dish.
Heat a little more oil in the pan and fry some finely chopped onion with crushed garlic. As soon as you put the onion in the hot fat, turn it down so that it cooks gently. Add any other finely chopped veg that you like, such as peppers, celery, carrots, leeks. (Not mushrooms at this stage - if you want these, they are best added later). Then add a tin of chopped tomatoes, and if the mixture seems a little dry, add some water.
Put some herbs over the chicken - tarragon is good, but you can also use thyme, basil, oregano or rosemary - and then add the veg mixture to the chicken pieces in the casserole. Put the lid on or cover with foil and cook it in the oven for at least an hour and a half. If you want to add mushrooms, clean and chop them (unless v small) and add half an hour before the end.