Scrub and pierce potatoes; place on a microwave-safe plate. Microwave, uncovered, on high until tender, about 15 minutes, turning once.
In a large bowl, combine the squash, zucchini, eggplant and leeks. Add salad dressing and toss to coat. Transfer vegetables to a grill wok or basket. Grill, uncovered, over medium heat until tender, 8-12 minutes, stirring frequently. Sprinkle with salt and keep warm.
Combine spreadable cheese and sour cream. With a sharp knife, cut an "X" in each potato. Fluff pulp with a fork. Spoon grilled vegetables over potatoes; dollop with cheese mixture. Garnish with basil.
Editor's Note: If you do not have a grill wok or basket, use a disposable foil pan. Poke holes in the bottom of the pan with a meat fork to allow liquid to drain.