Serves 4, preparation time 15 minutes, cooking time 20-25 minutes The Ingredients 60g/21⁄2oz butter 2 medium white onions, peeled and chopped 600g/1lb 5oz potatoes, peeled and chopped Salt and freshly ground black pepper 800ml/11⁄2pt vegetable or chicken stock 240g/81⁄2oz sorrel leaves, shredded (if you can’t find sorrel leaves, rocket works just as well) Single cream […]