Cut the fat layer from the meat down to the tendon layer with a sharp kitchen knife and score it crosswise.
Grind pepper and new spice in a mortar, rub the roast firmly all over, and finally massage with oil. Leave to work until the preparations for the potato gratin are done. 3.
Season with salt just before putting the roast on the stove, otherwise the salt will extract the juices from the meat. 4.
4. place the meat on the oiled oven rack.
For the gratin, remove the peel from the potatoes and cut them into 3 mm thick slices on a vegetable slicer. Spread evenly in a shallow buttered gratin dish, seasoning with salt and pepper and seasoning with marjoram crushed between the palms of your hands.
6. pour the whipped cream with milk, the liquid should just barely reach the surface.
7. place the dish on the bottom of the oven heated to 250-275 degrees. (After ten minutes, when the whipped cream already starts to make, place the prepared roast beef on the oiled roasting rack on the lowest shelf in the oven. Make sure the meat sits exactly over the roasting pan with the potatoes.
Continue to roast the meat on the highest heat for about 10 minutes. Then turn the heat down to 100 °C (I used 150 °C!). (Hot air 80 °C ) The meat in the n