Put the oat flakes, salt, cinnamon, sunflower seeds, raisins, vanilla sugar, brown sugar and hazelnuts together in a saucepan. Peel and quarter the apple, remove the core and grate coarsely. Add to the other ingredients in the saucepan. Pour in the water and milk. Bring everything to the boil briefly while stirring and remove from the stove. Roughly chop the walnut halves and fold into the leek, leave to soak for another 4 minutes.
We like to add a little maple syrup or brown sugar over the finished porridge!