1. Preheat oven to 200° C (Fan Forced). Remove all packaging.
2. Sprinkle curry powder on sheet of greaseproof paper, roll fillet in curry powder.
3. Melt butter in baking dish, add fillet, pour lemon juice over.
4. Bake uncovered for about 20 minutes or until tender. Baste meat frequently during cooking.
5. Meanwhile prepare the mustard sauce. Place chicken stock in a sauce pan, add lemon juice, french mustard and cream. Combine cornflour and water, stir into saucepan until sauce boils and thickens. Reduce heat, simmer uncovered for about 3 minutes. Season with salt and pepper.
6. Once cooked through, transfer to a plate: cover loosely with foil and rest for 10 minutes before carving.