Slow-braised pork shoulder with cider & parsnips

INGREDIENTS

• 2 tbsp olive oil
• 1kg/2lb 4oz pork shoulder , diced
• 2 onions , sliced
• 2 celery sticks, roughly chopped
• 3 parsnips , cut into chunks
• 2 bay leaves
• 1 tbsp plain flour
• 330ml bottle cider
• 850ml chicken stock
• handful parsley , chopped
• mashed potato and greens , to serve (optional)