To fully cook the insides of the dough, the dough would have to stay in the oil for a longer time, which would lead to the outsides becoming burnt. Punching a hole in the middle of the dough, however, allows the insides and the outsides to cook evenly, creating a perfect doughnut.
To fully cook the insides of the dough, the dough would have to stay in the oil for a longer time, which would lead to the outsides becoming burnt. Punching a hole in the middle of the dough, however, allows the insides and the outsides to cook evenly, creating a perfect doughnut.