Soak the dried haricot beans in cold water for 12 hours.
Put them in a saucepan with the onions, peeled, but left whole, adding salt, pepper, a bunch of mixed herbs and a very Uttle cold waterÃ¢â‚¬â€not more than double the amount of beans.
Simmer slowly till tenderj drain, and take out the bunch of mixed herbs.
Take just 3 or 4 tablespoonfuls of the beans, and crush them together with the boiled onions.
Thin this mixture with a little of the water used for boiling the beans and onions.
Stir in the butter, and add the rest of the beans.
Sprinkle with chopped parsley.