In a bowl add the flour, sugar and yeast and mix. Add the margarine, the egg yolk and gradually add the warm milk, stirring constantly.
Mix well with your hands until there is no more flour in the bowl.
Sprinkle a little flour on the table and knead the dough, you can add more flour if necessary, until the dough does not stick anymore, but the dough cannot be hard.
Knead for 10 minutes, cover and let rise for 30 minutes.
After the dough rises, sprinkle flour on the table and place the dough, sprinkle a little flour on the dough and roll it out with a rolling pin until it is about half a centimeter thick.
Cut the dough into 2-inch-wide by 4-inch-long rectangles. Make a 2-inch cut in the center of the dough lengthwise.
Pass one end through the cut to form the flipped underwear.
Fry in hot oil until golden. Remove from oil, drain on paper towels and roll in sugar and cinnamon.