This section is from the book "Soyer's Standard Cookery", by Nicolas Soyer. Also available from Amazon: Soyer's Standard Cookery.
Trim sweetbread and cut into four pieces. Trim four large mushrooms and tomatoes. Roll the sweetbread in flour, and put it between the mushrooms and tomatoes. Well butter your paper bag, and arrange the above nicely in the middle. Place one teaspoonful of breadcrumbs on top. Cover with a slice of fat bacon or ham, cut very thin. Flavor with sweet herbs as desired. Seal bag, and put on grid in hot oven. Allow twenty to twenty-five minutes (350 Fahr.).
Sweetbread (Fancy Method). Half a small onion, one slice of carrot, a little ham (fat and lean), and a little of the trimming, all cut into small dice. A small bunch of sweet herbs and thyme, parsley and bay leaves. Put these on the bottom of the paper-bag, which should be well buttered. Lard your sweetbread (if desired). Round it put three or four mushrooms, two or three tomatoes (skinned and all pips removed). Add a tablespoonful of stock Madeira, or sherry, according to taste. Seal bag. Put on grid. Allow twenty-five minutes in hot oven (350 Fahr.).
If color and thick sauce are desired, mix a quarter of a tea-spoonful of arrowroot with the vegetable, and a little burnt-sugar coloring. When you open the bag, remove the sweetbread gently. Place on dish. Remove tomatoes, mushrooms, etc., and place round it. Put the whole of the contents of the bag (juice included) in a strainer and press with a wooden spoon into a clean, hot bowl standing in boiling water, then pour the gravy thus obtained over the sweetbread.
 
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