Start a day ahead. Mix the olive oil, ginger, garlic, sherry and soy sauce together. Place the fillet in a shallow dish. Pour the marinade over the meat. Cover and place in the fridge overnight, turn occasionally.
Set oven at Gas Mark 6, 200ºC (400ºF). Lift the meat onto a roasting tin. Reserve the marinade.
Roast the fillet, allowing 8 minutes per pound for rare and 10 minutes per pound for medium, or use a meat thermometer. Brush the fillet during cooking with the marinade. When the meat is cooked wrap in foil to keep warm.
Deglaze the pan with the wine. Stir over a high heat gathering up the juices. Add a little water if necessary. Add in the scallions and season to taste. Slice the fillet and serve with the sauce.
Serving Suggestions
Fine French beans and small tomatoes, sautéed, are delicious with this dish.