Sweet potato fries as served at Dom Pepe restaurant in Sao Martinho.

Sweet potato fries are a true dessert, since the sugar in this starchy vegetable crystallizes to produce the fry's crunch. 

1. Cook the sweet potatoes in their skins for 60-75 minutes, depending on size.
2. Peel and cut the sweet potatoes into fries or cubes.
3. Fry in hot oil until the edges caramelize and turn slightly brown.
4. Salt and serve hot.