Separate the eggs, beat the egg whites until stiff. Beat the egg yolks with the salt and 4 teaspoons of sugar until frothy. Add the mineral water and gradually add the flour. Carefully fold in the egg whites and place the dough in the refrigerator for about 60 minutes.
Peel and slice the bananas. Peel the apples, remove the core, quarter the fruit and cut into thin slices.
Mix the bananas and apples into the batter. Heat some sunflower oil in a non-stick pan and add 10 g butter. Stir the pancake batter and add a ladle of batter to the pan. Bake the pancake on both sides for about 2 - 3 minutes until golden.
Repeat this process until the batter is used up. Sprinkle with sugar and serve immediately. The pancakes also taste cold.