1 Preheat the oven to 200°C, 400°F; gas 6.
Heat the oil in a large pan and fry the meat quickly on all sides to seal the juices.Transfer boththeoilandmeattoaroasting pan and roast for 45 minutes.
Leave to cool.
2 Melt the butter in a pan and fry the onion for 5 minutes until soft.
Add the mushrooms, parsley and seasoning.
Cover and fry for 5 more minutes.
3 Roll out the pastry to a rectangle large enough to completely cover the meat.
Spread 1/3 of the stuffing over the centre of the pastry and place the meat on top.
Spread the rest of the stuffing over the meat.
Dampen the edges of the pastry and fold them up over the meat like a parcel.
Trim.
4 Place the meat, join down wards, in a roasting pan.
Roll out the pastry trimmings and cut them into 'leaves' to decorate the top.
Brush the top with a little milk.
Increase the oven temperature to 220°C, 425°F; gas 7 and cook the beef for 40-45 minutes until the pastry is crisp and golden.
5 Transfer the meat to a serving dish and garnish with watercress.