Sweetbreads And Mushrooms - vinegar

Method

• To blanch sweetbreads, first wash in cold water, then place in a bowl and soak for about 2 hours in several changes of cold water . Pull off as much membrane and filament as you can without tearing the flesh. Soak for another 2 hours, this time adding 1 tablespoon of vinegar per quart of cold water. Pull off the filament and remove connecting tubes between lobes, if present. Place sweetbreads in a saucepan and cover by about two inches with boiling water. Add the salt and lemon juice (1 tsp salt and 1 tablespoon lemon juice per quart of water). Bring to a bare simmer and cook for 15 minutes. Drain and plunge into cold water for 5 minutes. Drain.
• When ready to cook, cut the blanched sweetbreads into bite-size cubes and brown them in the butter in a roomy skillet (You may need to brown them in two batches so as not to crowd them). Remove the sweetbreads to a plate. In the same skillet quickly brown the mushrooms over a brisk flame, adding more butter if needed. Add the lemon juice to the skillet and cook, covered, for 3 minutes.
• Return the sweetbreads to the skillet and add the chicken stock, tomato paste, sherry (I actually prefer dry marsala -- port or madeira would probably be OK, too), and bay leaf. Simmer, uncovered, over medium heat for 15 minutes. Add pepper. Dissolve the arrowroot in the white wine and add to skillet to thicken.
• The sweetbreads may be prepared ahead of time and refrigerated. Return to room temperature before reheating.