Cut the top off each onion and scoop out the centre using a teaspoon, then finely chop the scooped-out onion. Heat the oil in a frying pan, add the chopped onion and fry until softened and golden brown. Add the mushrooms and cook, stirring, for a further 5 minutes.
Meanwhile, bring a large saucepan of water to the boil, add the onion cups and simmer for 10 minutes or until they begin to soften. Drain well.
Add the bulgar wheat, parsley, salt, pepper and measurement water to the mushrooms and boil for 5 minutes, then reduce the heat, cover and simmer for a further 30 minutes or until the grains have softened, adding extra water if necessary. Stir in the sultanas, then spoon the bulgar mixture into the onion cups.
Place the onions in a roasting tin and cover with foil. Bake in a preheated oven, 190°C (375°F), Gas Mark 5, for 30 minutes.
Remove from the oven and take off the foil. Sprinkle over the Parmesan, if using, and bake for a further 10 minutes. Serve hot.
|