For frying foods:
You must let oil reach an extremely hot temperature before beginning to fry (but don’t let oil start smoking). Never add cold oil to the hot oil in the middle of frying, because the dough will absorb the cold oil. Only add more oil in between frying sessions and wait for oil temperature to rise before adding more dough. Remove fried sufganiot with a slotted spoon so that as much oil as possible remains in the pot.