Wash the fillet of beef and dab dry. Cut fillet into 4 equal pieces, season with salt and pepper. Heat 1 tablespoon of oil in a frying pan. Brown the meat all around. Put the meat on a piece of aluminium foil and place it on a baking tray.
Tip up the edges of the foil slightly so that the meat juice does not run onto the tray.
Wash the potatoes thoroughly and cut in half. Heat 2 tablespoons of oil in a frying pan and fry the potatoes in it in portions while turning for about 5 minutes. Add the potatoes to the meat on the baking tray and season with salt.
Cook both in the preheated oven (electric cooker: 200 °C/ circulating air: 175 °C/ gas: see manufacturer) for approx. 25 minutes.
Remove the meat after approx. 10 minutes (it is best to measure with a meat thermometer, core temperature 58-60°C), cover with aluminium foil and let it rest for approx. 10 minutes. Wash the rosemary, shake dry and remove the needles.
Add the rosemary needles to the potatoes about 5 minutes before the end of the cooking time.
Peel the garlic and cut into thin slices. Wash parsley, shake dry and chop the leaves finely. Peel the shrimps, except for the tail fin, and remove the intestines. Wash the shrimps and dab dry.
Heat 1 tablespoon of oil in a frying pan. Fry the prawns for 3-4 minutes while turning. Add garlic about 1 minute before the end of cooking time. Finally add parsley and season with salt.
Arrange the fillet of beef, shrimps and potatoes. Vegetables tossed in butter taste good with it.