1. To make the horseradish sauce, combine the cream, mayonnaise, horseradish, mustard, Worcestershire sauce, lemon juice and sugar. Season to taste with salt and freshly ground black pepper and then set aside. 2. Melt the butter over a medium heat in a frying pan. Add the leek and cook for 8-10 minutes until wilted. Add sugar and wine and cook gently for 20 minutes until the leeks have caramelised. 3. For the potatoes, melt the butter in a frying pan and fry the potatoes until soft and golden. 4. Meanwhile butter one side of each piece of bread and season. Fry the bread, on the buttered side for 1 minute and dust with pepper. Spread mustard on the soft, unbuttered side of the bread and reserve. 5. To assemble the sandwiches, layer the potatoes, leeks, horseradish and roast beef on the toasted bread, top with bread to form a sandwich, cut diagonally, secure with a toothpick and serve with watercress. ---------------------------------------------------------------------------
Nutrition
Ingredients
