Peel and halve the red onion and cut into strips. Mix vinegar and sugar. Fold in 3 tablespoons of oil in a thin stream. Season to taste with salt and pepper. Wash, peel and slice the beetroot, mix with vinaigrette.
Cover and place in a cool place.
For the sauce, peel and finely dice the onion. Melt the fat in a small pot. Fry the diced onion until transparent. Stir in flour, add white wine and stock. Simmer at low heat for about 10 minutes.
Wash the herbs and shake dry. Cut the chives into fine rolls. Finely chop parsley and marjoram, except for a little bit for garnishing. Stir the crème fraîche into the sauce. Place the sauce and herbs, except for 1-2 tbsp. chive rolls, in a tall container, puree and season to taste with salt and pepper.
Put the sauce back into the pot and keep warm. Cut the meat into about 12 medallions (each weighing about 40 g). Season with salt. Heat 2 tablespoons of oil in a large frying pan. Sauté the medallions in it on each side for 3-4 minutes.
Meanwhile, prepare the pasta in boiling salted water according to the instructions on the packet. Drain. Put the noodles back into the pot and mix with the sauce. Arrange noodles and medallions on plates, garnish with marjoram, possibly sprinkle with coloured pepper.
Arrange the salad in small bowls, sprinkle chive rolls on top, possibly sprinkle with coloured pepper.