Sauté the onions with the olive oil. Add tomato paste, sugar, raisins, bay leaf, parsley, and water and vinegar (or balsamic vinegar). Bring everything together to a boil. The ingredients have to simmer for about 45 minutes without a lid, until the liquid has largely boiled down.
Season the whole thing with salt and pepper.
Baguette or potatoes can be served with it.
A little hint:
Serve the salad lukewarm or cold. It both tastes very good.