Put some onions to cook in tarragon vinegar and water; when they are half done, add more water and throw in a little thyme and a leaf or two of bay; let it cook for one hour and pass it through a sieve. Melt some butter in a pan and thicken it with flour; put your vinegar to it and more water if you think it necessary; stir in salt and pepper and the yolks of two eggs or more, according to the quantity that you wish to make. Let it get thick, and just as you take it off the fire add a sprinkle of chopped parsley and a pat of butter. This is a useful sauce and it well repays the trouble.

[Mme. Spinette.]