Heat oven to 400° F. Place the eggplants cut-side down on a rimmed baking sheet and roast until very soft, 30 to 40 minutes; let cool. Scoop out the flesh from the eggplants and roughly chop.
In a medium bowl, stir together the eggplant, onion, basil, oil, vinegar, ¾ teaspoon salt, and ¼ teaspoon pepper. Serve with the vegetable chips.
