Blanch the sweetbreads in milk, bringing them to a bare simmer for 30 minutes. Peel the sweetbreads, removing any veins that should come away easily. Cut the sweetbreads into 4 cm (1½ inch) cubes. Wipe the cep mushrooms with a damp cloth and cut them in two.
Assemble the skewers, alternating the sundried tomatoes, ceps and sweetbreads. Season. Cook the speck on the barbecue until crispy