Preheat the oven to 175ºC (347ºF). Do not peel the potatoes. Wash them and cut them lengthwise into four parts. Pluck the rosemary needles from the stems and chop coarsely. Mix the potato slices with the rosemary, salt, pepper and 4 tbsp of olive oil. Place in an oven dish and roast in the middle of the oven for approx. 75 minutes.
Heat 2 tbsp of olive oil and the butter in a large frying pan on medium heat. First sear the sides of the roulade closed before cooking the roulade on all sides until brown. Set to low heat, add the shallot and capers. Deglaze with red wine and water. Set the lid of the pan at an angle and allow to cook gently. Every so often, spoon some of the cooking juices over the roulade. Allow the veal roulade to cook for approx. 75 minutes, by which time the core temperature should be about 69ºC (156ºF).
Blanch the sugar snaps for 2 minutes in salted, boiling water. Rinse with cold water and set aside in a sieve. Remove the roulade form the pan, allow to rest and remove its rope or net. Place the roulade in a fire-proof dish. Cover with the pancetta, basil and mozzarella.
Stir the crème fraîche into the cooking juices, adding salt and pepper to taste. Remove the potatoes from the oven and cover with aluminium foil. Set the oven to 200ºC (392ºF). Place the roulade in the oven for approx. 10 minutes until the mozzarella has melted. Heat 2 tbsp of olive oil in a wok, stir-fry the tomatoes and sugar snaps. Add pepper to taste. Salt is optional. Allow the roulade to rest before cutting it.
Use a sharp non-serrated knife to cut the roulade into slices. Serve with the potatoes, sugar snaps, tomatoes and sauce.