Two to three hours before eating, heat the roasting cream in a roasting pan. Rub the meat with salt and pepper. Brown well on all six sides to form a nice crust.
Insert roasting thermometer so that the tip comes to rest in the center of the roast. Place in the middle in the 100 °C hot stove.
For the cakes, cut the leek into very fine rings. Put them in a suitable bowl. Peel the potatoes. Grate half of them through the Bircher grater, the rest through the Röstiraffel to the leek. Add the flour. Mix the eggs and add them. Season and mix everything together well.
Once the roast thermometer reads a core temperature of 65 degrees, briefly open the oven door to allow a tiny bit of temperature to escape. Turn the oven temperature down to 70 degrees and remove the Reindl. Wrap the roast in aluminum foil without removing the thermometer. Put it back in the oven on the baking tray and keep it warm in the closed oven, maintaining the core temperature of 65 degrees.
Remove the drippings into the Reindl with the wine and reduce by half on the kitchen stove. Pour through a sieve into a small pan.
Add the gravy. Cook on low heat for a few minutes and season with pepper.
Melt the clarified butter in a frying pan. Using 2 tablespoons, place mounds of the leek and strawberry mixture into the pan and flatten.
Fry on each side over moderate heat for about ten minutes.