• 15 g/½ oz butter
• 1 tbsp sunflower oil
• 1 celery stick, finely chopped
• 1 onion, finely chopped
• 4 tbsp plain white flour
• 125 ml/4 fl oz/½ cup Fish Stock, weak
• Vegetable Stock or ready-made stock
• 750 ml/26 fl oz/3 cups milk
• 280 g/10 oz sweet potato, diced
• 2 bay leaves
• 1 long strip of lemon rind, pith removed
• 1 tbsp dried thyme
• ¼ tsp salt, plus extra to taste
• 700 g/1 lb 9 oz boneless, skinless salmon fillets, about 2.5 cm/1 in thick, cut into bite-sized pieces
• 4 smoked streaky bacon rashers
• freshly ground black pepper
• finely chopped parsley leaves, to serve
• smoked or sweet paprika, to serve

Heat the butter and oil in a large frying pan over a high heat. Reduce the heat to medium, add the celery and onion and fry, stirring, for 3–5 minutes until the onion is softened. Sprinkle over the flour and stir for 2 minutes to cook out the raw flavour. Pour over the stock and bring to the boil, stirring continuously to prevent lumps from forming. The mixture will be very thick and paste-like.

Slowly stir in the milk. Add the sweet potato, bay leaves, lemon rind, thyme and salt, then season with pepper. Cover and bring to the boil, then pour the mixture into the slow cooker.

Cover the cooker with the lid and cook on LOW for 4 hours until the sweet potato is tender. Gently stir in the salmon, re-cover and cook for a further 20 minutes until the salmon is cooked through and flakes easily.

Meanwhile, preheat the grill to high. When hot, grill the bacon for 2–3 minutes on each side until cooked and crisp. Drain well on kitchen paper, then chop very finely. Wrap in foil and keep warm.

When the salmon is cooked, remove and discard the bay leaves and lemon rind, and add a little more salt and pepper, if you like. Sprinkle with bacon, parsley and paprika and serve.