Heat the oil in a large frying pan over a medium-high heat. Fry the pork in batches, until just browned. Remove with a slotted spoon and put in a casserole. Add the onions to the frying pan and fry for 5 minutes, stirring, until just transparent. Place in the casserole with the pork.
Add the vegetables to the casserole, then pour over the cider and add the bay leaves. Put over a high heat and bring to the boil. Cover and simmer for 1 hour, or until the pork is tender.
Allow to cool, then freeze in portions for up to 3 months. Thaw for 24 hours in the fridge. To reheat, put into a large pan over a medium heat and heat until piping hot.
Stir the mustard and cornstarch into the creme fraiche, then stir into the casserole. Core and cut the apples into wedges. Add to the casserole and simmer for 5-8 minutes, or until the apples are tender and the sauce has thickened. Season and serve.