Mix lemon juice, 25 g sugar, 1 packet of vanillin sugar and 125-150 ml water. Peel, quarter, core and dice apples. Add to the lemon water, bring to the boil, cover and cook for 10-15 minutes.
Possibly mash with a potato masher. Allow to cool. Chop the hazelnuts. Separate eggs. Whisk egg yolks, 1 packet of vanilla sugar, salt and 175 ml milk. Add flour little by little. Stir in 75 ml milk.
Add 100 g hazelnuts. Beat the egg whites until stiff, then add 50 g of sugar. Carefully fold the beaten egg whites into the dough. Heat 1 tbsp. clarified butter in two large frying pans. Pour in 1/4 of the dough each.
Bake at low heat for 4-5 minutes until golden brown. Quarter the sardines with a pallet, turn them over and bake from the other side until golden. Then tear into pieces with 2 forks. Remove the finished Kaiserschmarrn from the pan and keep warm.
Bake the rest of the dough in the same way. Arrange the sardines on plates with apple compote and sprinkle with 25 g hazelnuts.