Make waffles as usual but reduce the amount of sugar to 1/4. Bake the waffles and let them dry for half an hour on a baking sheet so that they become a little crispy.
2
Mix together sour cream and pepper. Add salt and lemon juice to taste.
3
Scrub the Jerusalem artichokes well and cut into thin slices with a mandolin or knife. Let them soak in cold water before you dry them well with a kitchen towel. Fry in sunflower oil over medium-high heat until golden. Sprinkle with salt.
4
Boil the water together with lemon juice and sugar. Let cool.
5
Cut the red onion into strips and add to the lemon-sugar water. Let set for about 30 minutes. You can also make this the day before.
6
Fry the burger on both sides for about 2 minutes, and serve in a waffle with sour cream, pickled red onion and rocket.
