This dish embodies the light, fragrant flavors of Touraine or Angevin cuisine. For best results, use very fresh foraged mushrooms like small meadow mushrooms, chanterelles, or tiny ceps.
Skin the sweetbreads and remove any fatty or blood-stained parts. Wrap in a clean cloth, place on a plate, top with another plate and a weight, and press for 1 hour. Unwrap to reveal purified sweetbreads.
Meanwhile, peel and thinly slice the carrots. Trim, wash, and cut the leeks into fine julienne strips.
Pour 20 cl of water into a snug casserole dish. Add the sweetbreads and salt, cover, and cook for 10 minutes. Add the vegetables and cook covered for another 15 minutes. Stir in the butter in pieces, then remove from heat.
Peel and finely chop the shallot. Clean the mushrooms by trimming the earthy stems (avoid washing). Blanch for 2-3 minutes, then simmer in a small saucepan with the shallots, cream, salt, and pepper for about 10 minutes, stirring occasionally.
Gently reheat the sweetbreads, adding 1 tablespoon white wine vinegar and a pinch of mustard. Transfer to a deep dish, fold in the creamy mushrooms, cover to meld flavors, and serve warm.
Pro tip: Fine julienne cuts for leeks and carrots elevate the presentation.
Source: Regional Cuisines of France, Channel Editions.
