Beef Medallions in Peppercorn Sauce

1 lb of beef tenderloin
4 tsp wholegrain mustard
450g/1lb pack herby pork and beef sausages
2 tbsp olive oil
1 large onion, cut into wedges
2 x 25g/1oz packets creamy pepper sauce
225ml/8fl oz beef stock

1. Cut the beef tenderloin into medallions and flatten each slightly with a rolling pin between some plastic film. Spread a thin layer of mustard over one side of each beef medallion.
2. Prick the sausages with a fork and wrap a beef medallion around each one. Secure with a cocktail stick.
3. Heat the olive oil in a frying pan and fry the beef medallions for 8-10 minutes, turning frequently until browned. Remove and set aside. Add the onion and cook for 8-10 minutes until golden brown, stirring often.
4. Sprinkle the sauce mix over the onion and stir in 570ml/1 pint water. Stir in the stock. Bring to the boil, return the beef medallions to the pan and simmer, uncovered, for 20 minutes. Season to taste and serve with creamy mash.