Clean the mushrooms and cut into slices 12 cm thick. Rinse carrots, remove peel and cut in half lengthwise. Cut halves first into 3 cm long pieces, then into 3 mm narrow slices. Peel onions and garlic. Finely dice onions, press garlic through a press.
Bring garlic, onions, mushrooms and carrots to a boil with vegetable soup in a wide saucepan, cover with lid and simmer at low temperature for 15 minutes. Cut the pike-perch into large pieces, dry and season with 4 tbsp. of lemon juice, salt and pepper.
After 5 minutes, place the pike perch on the vegetables and cook at low temperature for 8-10 minutes, remove and keep warm. Stir crème fraîche into the vegetables and season with 1 tbsp juice of one lemon, salt and pepper. Cut cress from the bed. Arrange the pike perch on the vegetables and bring to the table sprinkled with cress. Serve with boiled, peeled potatoes.
Tip: You can get evenly thick mushroom slices if you cut the mushrooms with an egg slicer.