Strewing in flour or breadcrumbs
Heat the fat in a pan. It will start to swell after some time. Strew in a pinch of flour or breadcrumbs into the fat.
How do you check if oil or other types of fat used for deep-frying already has the right temperature? If you place the parts which will be fryed too early in the fat, they unnecessarily absorb fat and will not turn out crunchy.