Sweetbreads with Herbs and Mushrooms

Sweetbreads are often hard to come by, and are costly. Many butchers save all their sweetbreads for their restaurant trade, so you might have to pressure your local meat market to put some away for you. They must be absolutely fresh, and served the day they are bought. Sweetbreads always come in pairs and must be thoroughly washed, blanched, and the membranes and tubes removed. This takes a bit of trouble, but as the French say, "La grande cuisine cannot wait for man-man must wait for la gr