White Butter Sauce

Finely chop 2 or 3 grey shallots. Reduce it in 5 cl of wine vinegar.
When reduced, remove the remaining vinegar; add 10 cl of dry white wine, reduce it.
When reduced, remove the remaining wine, and let it cool down.
Then, put it over a very low heat, and add little by little pieces of slightly salted butter.
When you begin to add the butter, you have to keep stirring gently.
Add butter up to the requested quantity.
The white butter sauce goes with scallops, sea bass or pike perch
and can be served with potatoes and green asparagus