2 jacket potatoes
200g/7oz button or chestnut mushrooms, sliced
2 large onions, sliced into thin rounds
mustard, horseradish sauce, Worcestershire sauce or b茅arnaise sauce
salt and freshly ground black pepper
2 tbsp olive oil
olive oil, for brushing
knob of unsalted butter
2 large knobs of butter
2 lean rump or sirloin steaks (150g/5陆oz each)