For the slow cooker

Preheat the slow cooker, if required. Heat half the oil in a large flameproof casserole over a high heat and season the pork belly with salt and pepper. Add the pork (in batches, if necessary), skin-side down, and cook until it turns golden and begins to crisp a little. Remove and sit the pork on kitchen paper to drain

Heat the remaining oil in the casserole over a medium heat, add the onion, and cook for 3–4 minutes until soft. Then stir in the garlic and cook for a minute more. Increase the heat and add the sherry vinegar, letting it simmer for 2–3 minutes. Pour in the wine and continue to boil for a few more minutes until the alcohol evaporates.

Transfer everything to the slow cooker, including the pork. Pour over the stock and stir in the prunes, sage, and celeriac. Cover with the lid and cook on auto/low for 8 hours. Taste and season more if needed, and serve with creamy mashed potatoes.

For the traditional method:

Preheat the oven to 160°C/ 325°F/ gas 3. Heat half the oil in a large flameproof casserole over a high heat and season the pork belly with salt and pepper. Add the pork (in batches, if necessary), skin-side down, and cook until it turns golden and begins to crisp a little. Remove and sit the pork on kitchen paper to drain.

Heat the remaining oil in the casserole over a medium heat, add the onion, and cook for 3–4 minutes until soft. Then stir in the garlic and cook for a minute more. Increase the heat and add the sherry vinegar, letting it simmer for 2–3 minutes. Pour in the wine and continue to boil for a few more minutes until the alcohol evaporates.

Add the stock and stir to scrape up the bits from the bottom of the casserole. Return the pork to the casserole and stir in the prunes, sage, and celeriac. Bring back to the boil, cover, and put in the oven for 2.5–3 hours. Check occasionally that it’s not drying out, topping up with a little hot water if needed. Taste and season more if needed, and serve with creamy mashed potatoes.