4 medium sweet potatoes (about 2 pounds), peeled and cut into 1/2-inch-thick
Vegetable oil, for frying
1 teaspoon furikake (see Note)
In a large bowl, cover the sweet potato batons with cold water and let them stand for 2 hours.
In a large pot, heat 4 inches of vegetable oil to 300°. Drain the sweet potato batons and pat thoroughly dry with paper towels. Working in batches, fry the sweet potatoes until softened but not browned, about 4 minutes. Transfer to a paper towel-lined platter to drain and cool.
Heat the vegetable oil to 350°. Fry the sweet potatoes again until golden, about 4 minutes. Transfer to a paper towel-lined platter to drain. Sprinkle with furikake and salt and serve immediately.
Furikake is a Japanese seasoning of dried chiles, nori and sesame that's available at Asian markets. You can substitute chile powder.