Put the cider into a large casserole with the bacon joint, which should have been soaked overnight in cold water if necessary. Add the peeled onions and cover with a lid. Cook for one and a half hours at 325°F, 170°C, gas mark 3. Remove from the oven and turn the bacon over. Core the apples but do not peel them. Arrange round the bacon, baste and return to the oven for a further thirty minutes.
Transfer the bacon to a heated serving dish and arrange the onions and apples round it. Pour the cider into a pan, add the flour mixed to a smooth paste with cold water and the redcurrant jelly. Bring to the boil, stirring continuously and boil for three minutes. Serve in a sauceboat.