Dab the meat dry and cut into medallions. Heat 2 tablespoons of oil in a large frying pan. Fry the medallions in it in portions on each side for about 3 minutes.
In the meantime, rinse and drain the beans. Drain the corn. Cut cheese into small cubes. Wash parsley, shake dry and chop. Wash and halve the tomatoes. Clean, wash and dry shake the arugula.
Peel onions and cut them into fine rings. Season medallions with salt and pepper, remove and wrap in aluminium foil. Deglaze roast with 7-8 tablespoons of water and vinegar, bring to the boil and stir in the stock.
Let the onions soak for 1-2 minutes. Leave to cool down a little.
Whip 1-2 tablespoons of oil into the marinade. Season with salt, pepper and 1 pinch of sugar. Mix prepared salad ingredients and marinade. Arrange salad and medallions on a plate.