Pat the veal dry and pound each slice between two sheets of parchment to about 3 mm / 1/8 inch, working from the center outward. Season the slices with the pepper only. Trim any slice that is much larger than the others so the rolls come out even.

Lay a slice of prosciutto on each piece of veal, trimming any overhang. Add 2 sage leaves and about 1 tablespoon of Parmigiano. Roll up from a short side, tuck in the edges, and secure with a toothpick or kitchen twine. You'll have 8 rolls.

Spread the flour on a plate and turn each roll in it, shaking off the excess. Heat the oil and butter in a 30 cm / 12-inch deep sauté pan over medium-high heat until the butter foams. Sear 4 rolls for about 4 minutes, turning, until pale gold on all sides. Move them to a plate and repeat with the remaining 4.

Lower the heat to medium and add the onion, carrot, celery and 1/4 tsp salt. Cook, stirring, for about 6 minutes until soft and pale gold. Pour in the wine, scrape up the browned bits, and cook for about 2 minutes until the smell of alcohol fades and the liquid has reduced by about half.

Stir in the tomatoes and water. Return the rolls and any plate juices to the pan in a single layer and bring to a gentle simmer. Cover with the lid slightly ajar and cook for 30 minutes, turning the rolls once at the 15-minute mark, until a paring knife slides in with almost no resistance. Keep the bubbles lazy.

Taste the sauce and add salt if needed. If it looks thin and doesn't coat the back of a spoon, uncover and simmer for 3 to 5 minutes more. Remove every toothpick and serve the rolls with the sauce spooned over.