Pour oil in a skillet or deep fryer, make sure you have enough oil so the donuts will be at least half immersed in oil when puffed.
You want the oil hot but not too hot about 370 to 375 F (see my tips for perfect donuts here).
Use the donut centers to test oil. If the dough takes more than 30 seconds to float, it means the oil is still not hot enough
If it bounces up before 30 seconds, reduce the heat slightly.
Gently add the cold donuts to the oil – you can add two to three depending on the size of your skillet.
Let the donut cook 30 seconds then flip, so it puffs the other side too.
Continue to cook gently turning as necessary until golden brown.
Remove and drain on a paper hand towel for a minute.