Trim the veal kidneys of any fat and cut into large dice. Dice the bacon breast and blanch it briefly.
Cut the champignon mushrooms into pieces and blanch lightly.
Peel and dice the chayotes. Sweat them gently over low heat in butter until foamy. Season and set aside.
Prepare the sauce: Finely chop the shallot and sweat in butter without coloring. Deglaze with white wine, reduce, then add veal stock and thyme. Reduce further, strain, and stir in violet mustard from Brive. Season with salt and freshly ground pepper. Finish with cream and set aside.
Thread the kidney pieces, mushrooms, and bacon onto skewers (two per person). Grill or sauté until golden.
Arrange the chayote brunoise in a circle on the plate. Cross the skewers on top, warm the sauce, and glaze the skewers. Surround with a sauce cordon.
Finish with chopped chervil and diced tomato.

Chayote (also known as Christophine)

The veal kidney, trimmed of its fat membrane.
Chayote, or christophine (also called chouchou, chuchu, chow chow, or mirliton), is a versatile vegetable I first encountered on the island of Saint-Barthélemy. Its mild flavor pairs beautifully in this dish.