Brown the bacon, onion and sauerkraut with a little sweetener in a saucepan. Remove from heat and add the chopped, peeled apple pieces and spring onions cut into rings and mix.
Spread everything in a baking dish. Now cut the fish into small strips and distribute them on the sauerkraut.
Mix the sour cream, 2 egg yolks, grated cheese, salt and pepper and spread over the sauerkraut and fish mixture. Place in the preheated oven at 200 ° C for approx. 20 minutes.