These tender and delicately flavoured meats come exclusively from young animals, most often lamb or veal. Veal sweetbreads are the most commonly used by chefs today and this recipe is a classic Dijon dish.

Clean and blanch the sweetbreads: Place the sweetbreads in a dish of cold water for ten minutes or more. Blanch them for 10 minutes with the salt and lemon and then refresh under cold running water. Carefully pull off all the tough and fibrous skin to clean them.

Braise the sweetbreads: Preheat the oven to 400 ° F. In a roasting pan, melt the butter and add the clean sweetbreads with the onion, carrot, celery branch, bay leaves, thyme sprigs and tomato. Bake 20 minutes in the oven and turn over the sweetbreads. Add the stocks and cook for another 15 minutes. Remove from the oven, and place the sweetbreads on a large plate to allow cooling and reserving of the juice. Raise oven temperature to 450 °F.

Make the sauce: In a medium saucepan, melt ½ tablespoon of butter on low heat. Add the shallots and cook for a minute, then add the wine and simmer until reduced by half. Add the cooking juice and vegetable from the roasting pan and simmer until slightly thick. Add the cream and strain the sauce through a fine sieve into a new saucepan and reserve.

Finish the sweetbreads: On a tray divide the sweetbreads to 8 little piles On a slightly floured surface, roll the puff pastry to 3 minimitres tick. Cut the dough into rectangle pieces and wrap each sweetbread portion with the pastry, and place them on a tray covered with parchment paper. Make an egg wash with the yolk and water and mix well. Brush each portion of egg wash and bake in preheated oven for about 20 minutes or until golden brown.

Bring the sauce to a boil and whisk in the grainy mustard, then off the heat, whisk in the remaining butter. Serve sweetbread individually over 3 to 4 ounces of sauce on preheated warm plates.