Normandy-style pork and cider casserole

Method

1. Heat a glug of oil in a large pan. Add the pork in 2-3 batches and brown for 6-8 minutes per batch, transferring with a slotted spoon to a plate. Add the whole shallots and cook for 2-3 minutes until browned, then transfer to a plate.
2. Meanwhile, fry the bacon in a large flameproof casserole with 
a splash of oil for 4-5 minutes until crisp, then scoop out with a slotted spoon and set aside. Put the onion and celery in the casserole with the butter, then cook for 6-8 minutes over a medium-high heat until softened.
3. Add the pork, bacon, 300ml cider and stock, bring to the boil, then turn down the heat. Partially cover the casserole, then simmer gently for 1 hour. Add the shallots, then cook for another 1-1½ hours until the pork is tender (see make ahead).
4. Mix the cornflour in a small bowl with the 1 tbsp cider, add to the casserole and cook for 5 minutes, stirring, to thicken the sauce. Stir in the crème fraîche, mustard and most of the tarragon, then season and add a splash more cider. Serve scattered with the remaining tarragon with crusty bread and potatoes or rice.