Preparation
Mix the water and the egg yolk. In a large bowl mix the flour and the egg/water mixture.
Mix and knead the dough for about 5 minutes until it is compact. Cover with a damp cloth and set aside for 5 minutes.
Meanwhile heat a deep fryer to 170C, or fill a frying pan with lots of oil and heat. Take a small ball of the dough, the size of an egg and mold into a flat circle, about 1 cm thick. Fry until golden brown, turning regularly. Turn out onto crumpled absorbent paper and leave to cool slightly.
Split them open and fill with cheese, ham, butter, honey or whatever you wish. Serve immediately.