Heat the oven to 190°C (170° fan) 375°F gas 5. Grease 2 individual baking dishes.
Heat the oil in a frying pan and brown the pork on all sides. Remove and set aside. Add the onion to the pan and cook for a few minutes until beginning to soften.
Toss the potatoes and apples in the melted butter and thyme and season to taste with salt and pepper.
Add the pork and onions and divide between the baking dishes. Pour over the pan juices. Cover with foil and cook for 20 minutes.
Remove the foil and cook for a further 20-30 minutes until the potatoes are tender and the top is lightly browned.