Cut the onions into small pieces and mix with butter, salt, pepper and sugar in a saucepan and simmer covered over a low fire for a good 1 hour until the onions are soft. Then add vinegar, wine and grenadine and boil down properly for 1 hour without the lid. The mass should have a jam-like consistency at the end.
Pour the onion into small glasses and put in a cool place. Shelf life approx. 1/2 year.
Goes wonderfully with fondue, lamb, cheese and sauces.