Sweetbread Patties

This is a cross-reference entry: the method lives with the chicken patty filling, and all that changes is the meat. The work that matters is in the two words "prepared sweetbreads," which the book assumes you already know how to produce.

• What "prepared" meansSweetbreads are soaked in several changes of cold water, or cold water with a little salt, for an hour or more until they lose their blood, then simmered gently 15 to 20 minutes in acidulated water. Drain, cool under cold water, and peel away the membrane, tubes and connective tissue before dicing. Skipping the firming step makes them impossible to cut cleanly.
• Which sweetbreadsThe recipe does not specify, but veal sweetbreads were the usual market item. What butchers sold as a pair was the longer throat sweetbread (the thymus) and the rounder heart or stomach sweetbread (in fact the pancreas). They are a special-order item at most butchers now. Lamb sweetbreads work and are smaller and milder; both are highly perishable and should be soaked the day they come home.
• The filling itselfPatty fillings of this period are generally diced meat bound in a thick white sauce, on the order of 2 tablespoons butter and 2 tablespoons flour to a cup of milk or light cream and stock, seasoned with salt and pepper and sometimes sherry, lemon or nutmeg. It should mound on a spoon rather than run. Check the chicken patty entry for the book's own proportions.
• QuantityA pair of veal sweetbreads will give you roughly a cup or so of diced meat once trimmed, which with its sauce fills several small patty shells; how many depends on the size of the cases.
• Patties are the shells, not the mixtureIn a book of this period a "patty" is a puff-paste case, what a caterer would call a vol-au-vent or bouchée. Frozen puff pastry shells stand in exactly; bake them per their package and fill them just before serving so the pastry stays crisp.
• Cook the sweetbreads throughOffal deserves the same care as ground meat: simmer until firm and opaque all the way through, and reheat the finished filling to a full bubble in the sauce rather than merely warming it.
• Stretching itSautéed mushrooms, a few peas, or diced ham are common period pairings and will stretch a single pair of sweetbreads. Add them to the sauce, not to the simmering water.