Heat the oven to 180C gas mark 4
Core and slice the apples and place in a casserole dish. Gently fry the onions in half the olive oil until they start to brown.
In a separate bowl, mix the cubed pork with the flour to provide a light coating. Remove the onions to the casserole dish, add the rest of the olive oil to the pan, brown the pork and add to the casserole dish.
Meanwhile, heat the chicken stock and the cyder vinegar until just simmering; turn off the heat and add to the casserole dish. Add the mustard, place the dish in the oven and braise for about an hour until bubbling well.
The sauce around the pork should be thick and rich. Check the seasoning and add salt if required. Just before serving, add the tarragon and freshly ground black pepper.
Serve with mashed potato and seasonal green vegetables.
Ideal with a glass of Aspall Premier Cru Dry Cyder.