Step 1

Preheat oven to 160°C. Toss pork in flour and season. Heat oil in a flameproof casserole over medium-high heat. Add pork and cook, turning, for 8-10 minutes until browned. Remove pork and set aside.

Step 2

Drain fat, leaving 1 tbs in the casserole, then return to medium heat. Add onion, celery and carrot. Season with salt and cook, stirring, for 6-8 minutes until slightly caramelised. Add garlic, bay and thyme and cook for 2-3 minutes until fragrant. Add tomato and cook for 5 minutes, then add Pedro Ximenez, wine and stock and bring to the boil. Return pork to casserole. Cover surface with baking paper, then cover with a lid and bake for 3 hours or until tender.

Step 3

Remove pork and set aside. Strain braising liquid and return to casserole over medium-low heat. Cook, skimming impurities from the surface, for 35 minutes or until reduced. Return pork to casserole.

Step 4

Meanwhile, place celeriac and potato in a large pan of cold, salted water. Bring to the boil, then simmer for 15-20 minutes until tender. Drain, then whiz in a food processor with butter until smooth. Season.

Step 5

Serve pork with puree and sauce.