2 pounds unpeeled sunchokes (also called Jerusalem artichokes), scrubbed
Vegetable oil (for frying)
1 tablespoon salt
1 1/2 teaspoons minced fresh rosemary
Fill large bowl with cold water. Slice sunchokes into thin rounds (about 1/16 inch thick), immediately dropping into bowl of water to prevent browning. Rinse and drain 3 times. Pat very dry with paper towels.
Pour enough oil into large deep skillet to reach depth of 1/2 inch. Submerge bulb of deep-fry thermometer into oil; lean top of thermometer against skillet rim. Heat oil to 375°F. Mix 1 tablespoon salt and rosemary in small bowl. Using fingertips, blend well, rubbing salt and rosemary together.
Working in batches, fry sunchoke slices until golden brown, stirring occasionally, 3 to 4 minutes. Using skimmer, transfer chips to paper towels to drain. Sprinkle chips with some rosemary salt. DO AHEAD: Chips can be made 2 hours ahead. Let stand at room temperature.
Mound chips in bowl and serve.
From Bon Appetit, Jan. 2010.