For the apple sauce
Mix the lemon juice with 100 ml water.
Add the sugar and bring to the boil.
Add the apples, cinnamon stick and the lemon zest and boil until the apple crumbles.
Set aside and leave to cool.
Remove the cinnamon stick and the lemon zest and stir occasionally.
For the latkes
Grate the potatoes and the onion into a bowl and pour away the resulting liquid.
Stir in the the meal and the egg yolk to create thick mass.
Season with salt and ground black pepper.
Place a spoonful of the mass into a pan and fry on both sides in a little oil on a medium heat until golden brown.
If desired, keep warm in the oven (lowest setting) until all the latkes are done.
Serve with apple sauce.