Crispy Smashed Potatoes With Rosemary

A smashed potato has more surface area than a roast one, which is the entire reason for smashing it.

Everything else in the method exists to make sure that surface meets hot oil dry rather than damp.

Two things make these crisp: boiling the potatoes until they are genuinely overdone, and letting the steam escape before they meet oil.

A potato smashed while wet fries in its own water and comes out pale.