To half a pint of good stock add two good sprays of fresh tarragon, simmer for quarter of an hour in a stewpan and keep the lid on. In another stewpan melt one ounce of butter and mix it with three dessert-spoonsful of flour, then gradually pour the stock from the first stewpan over it, but take out the tarragon. Mix well, add a teaspoonful of finely chopped tarragon and boil for two minutes.
Source: ''The Cook's Decameron: A Study In Taste, Containing Over Two Hundred Recipes For Italian Dishes'' from a project that puts out-of-copyright texts into the public domain. This is from a *very* old source, and reflects the cooking at the turn of the last century. Update as necessary.