Very easy and quick to make and tastes delicious.

Best served with either mashed or sauteed potatoes (or possibly polenta) and a crisp green vegetable such as kale.

1. Heat 1 tablespoon of the olive oil and all of the butter in a heavy-based frying pan. Fry the onions over a low heat for 15-20 mins or until soft. Season lightly with salt and freshly ground black pepper, place in a bowl and set aside to keep warm.
2. Heat the remaining olive oil in the frying pan until hot. Season the calf's liver with salt and freshly ground black pepper and fry for 30-60 secs (it should remain pink inside). Remove and mix with the onions in the bowl.
3. Put the liver and onions back into the frying pan. Quickly heat through and add the vinegar, crème de cassis and parsley.
4. Serve at once onto hot plates.