Put all the ingredients from the carrot to the vinegar in a deep pot and bring to the boil, boil for 3 minutes, then gently add the sweetbreads and stir well. The sweetbreads must be well covered with liquid; if not, top up with hot water. Bring back to the boil and simmer for 5 minutes before removing the pot and leaving the sweetbreads to cool in the poaching liquor. Once cooled, drain them and pull any fatty bits off, then lay them on a plate and sit an identical plate on top. Place some weights (e.g. cans of food) on the upper plate and leave for 2 hours.
Meanwhile, make the polenta. Sauté the onion, rosemary and garlic in the olive oil until the onion softens. Add the salt and stock and bring to the boil. Turn to a simmer, then slowly trickle the polenta in, whisking as you go to prevent lumps forming. When all the polenta has been added, remove the whisk and stir with a spoon. Return to the boil and simmer for 1 minute. Pour the polenta on to an oiled plate and leave it to cool.
When you’re ready to serve the dish, cut the polenta into wedges and place on an oiled tray in a hot oven (220°C/425°F/Gas 7) for at least 5 minutes. Heat the olive oil and butter in a frying pan over a high heat until the butter starts to brown. Add the sliced onion and fennel seeds and sauté, stirring, for 1 minute. Add the sweetbreads and fry until golden on both sides, then add the lemon juice, zest and chicken stock. Bring to the boil, taste for seasoning and stir in the parsley. Spoon the sweetbreads on to the hot wedges of polenta and enjoy.
© 1997 Peter Gordon. All rights reserved.