Sauce Olives-Xérès

The best sauce ever. It takes a while, but God, it is worth it.

Put onions in a pot. Start frying them a bit hard to give them colour and then reduce to the lowest fire possible. Cover the pot and wait. Add olives.
In a bowl, mix some sherry and some cornflower. Add to the onions. Let simmer for a long long time depending on your tast and what you want to do with this. Add some garlic.

One can use it as a sauce over pasta or meat and for that add some crême fraîche or milk in it.
Otherwise you could add vegetables in it such as carrots, tomatoes, potatoes, turnip etc.. Add water to cover everything and let simmer until the vegetables are cooked.