Ask any south islander - where the best potato's come from ... and they will say 'Oamaru Jersey Bennies'.
It is almost a religion... the Jersey Bennie is bought in boxes - and must be fresh.. you tell this by gently scrapping the potato with your finger nail. The father in law - also squeezes them to make sure they are firm... he is very particular with his Bennie's!
Basically gently wash off the dirt with warm water - and boil with mint - and you too will be a convert.
By the way Fisher and Paykel (believe it or not) have a smashing recipe including Bennie's below: