Begin by preparing the cinnamon sugar. Mix together the sugar and cinnamon in a small bowl and set aside.
Place the dinner rolls on a baking tray lined with parchment paper, ensuring they are evenly spaced. Arrange them in four rows of three.
Let the rolls thaw and rise for about 3 to 4 hours in a warm place.
Heat a few inches of vegetable oil over medium heat until it reaches 325°F.
Once the oil is hot, carefully drop the dough in batches to avoid overcrowding. Fry each side until golden, approximately 2 minutes, then flip them over to cook the other side.
Remove the donuts from the oil using a slotted spoon to drain any excess oil, then roll them in the cinnamon sugar.
Enjoy your warm, homemade donuts!