Put the flour, egg, sugar, butter, a pinch of salt and 1 teaspoon lemon juice in a bowl and knead into a dough with your hands or a dough hook. Shape this dough into an approx. 5 - 6 cm thick roll and let it rest for 2 hours in the refrigerator.
Heat and grease the waffle iron (if necessary). Cut slices about 1 cm thick from the roll, place one after the other in the center of the waffle iron and bake.