Clean the spinach, wash it and let it drain in a sieve. Heat oil in a pot. Sauté the spinach in it over a low heat for 1-2 minutes while stirring. Season with salt and pepper. Peel and finely chop the onions. Wash the cod and remove any bones. Cut fish into small pieces
Puree the egg white and fish for approx. 30 seconds with a hand blender. Add spinach, 2/3 of the onions, juice of 1/2 lemon and 300 g cream. Puree for another 30 seconds. Season with salt, pepper and paprika powder. Grease 6 box moulds (each 9 x 6 x 4 cm) and spread the fish mixture in them. Fill a bowl with hot water and place it on the fat pan of the oven. Place terrines in the water bath and cook in the preheated oven (electric cooker: 175 °C/ circulating air: 150 °C/ gas: see manufacturer) for approx. 35 minutes
In the meantime, wash the dill and chop finely, except for a few flags for garnishing. Mix quark with 4 tablespoons of cream, chopped dill, remaining onions and lemon juice. Season to taste with salt, sugar and pepper. Let the terrine cool down for about 15 minutes and turn out of the tin. Arrange on plates and garnish with dill flags. Add quark