Jerusalem Artichoke Chips with Lemon Thyme Dip

In a small bowl stir together mayonnaise, zest, lemon juice, thyme, and salt and pepper to taste until combined. In a 4-quart heavy kettle heat oil over moderate heat until a deep-fat thermometer registers 325 °F. While oil is heating, cut unpeeled artichokes lengthwise into 1/8-inch-thick slices. Fry artichokes in 2 batches in oil 1 1/2 minutes (artichokes will not color) and transfer to paper towels to drain. Heat oil to 350 °F. Return artichokes in 2 batches to oil and fry, stirring occasionally, until golden and crisp, about 5 minutes. Transfer chips with a slotted spoon to clean paper towels to drain and season with salt. Serve chips with dip.