To fry the vegetables: Fill a heavy-bottomed pot fitted with a deep-fry thermometer with 2 inches vegetable oil and heat to 375 degrees F over medium-high heat. Line a baking sheet with paper towels. Working in batches, fry the potato and eggplant slices until deep golden brown and just soft on the inside, 2 to 3 minutes. Use a slotted spoon to transfer the vegetables to the prepared baking sheet. Bring oil back to temperature between batches. Fry the cauliflower at 375 degrees F until golden brown and softened, 1 to 2 minutes. Use a slotted spoon to transfer to the paper towel lined baking sheet and season all the vegetables with 1 teaspoon salt.