Combine flour, eggs, yogurt, sugar, salt and vanilla sugar in a large mixing bowl.
Mix well. Set the dough aside for 30 minutes.
Form the dough into balls with a 2-inch diameter.
Heat the vegetable oil to 365 degrees F (190 degrees C) in a large pot or deep fryer over high heat. It is best to use a basket or slotted spoon for deep frying the sufganiyot, as the oil will be extremely hot. Deep fry the dough in the oil.
Let the sufganiyot cool and drain on paper towels.
