Cut the leek into small pieces and fry briefly in a little oil. Core the apples and process together with the leeks in a blender to a pulp. Set the porridge aside.
Chop the bananas with a fork and mix with the baking soda. Also put aside.
Mix the flour, oat flakes, walnuts and baking powder, add salt, pepper, caraway seeds and mineral water and mix with a mixer. Now add the banana mixture and stir again.
Finally, add the apple and leek mixture. Mix everything well and then pour onto a greased tray. Bake in a preheated oven at 180 ° C with convection for about 30 - 40 minutes.
Then let cool for about 20 minutes and cut. A green salad can be served as a side dish.