Here you are Sam - this is the recipe I use for my hubby and he loves it.
1 tbsp vegetable oil
1 onion, sliced
225g/8oz potatoes, cubed
2 medium leeks,sliced
1.2 litres/2 pints vegetable stock
150ml/5fl oz double cream or crème fraîche
salt and freshly ground black pepper
Method
1.Heat the oil in a large pan and add the onions, potatoes and leeks. Cook for 3-4 minutes until starting to soften.
2.Add the vegetable stock and bring to the boil. Season well and simmer until the vegetables are tender.
3.Whizz with a hand blender or in a blender until smooth. Reheat in a clean pan, stir in the cream or crème fraîche, heat through and serve.