Grilled Summer Vegetable Salad

Peel back husks on corn and remove corn silk. Replaces husks to cover ears and put ears in large bowl with water to cover, soak 30 minutes. Meanwhile, preheat grill to medium. In small bowl, stir together 2 tablespoons oil and chili powder. brush mushrooms,squash, and onion with seasoned oil. Drain corn, transfer to grill and grill about 15 minutes , turning after 7 minutes, or until husks start to char. Remove and let cool. Add remaining vegetables to grill in batches. Arrange peppers, skin side down, add mushrooms, squash and onion slices and grill, turning 7 minutes or until tender. As the vegetables are done, transfer them to a platter to cool. Peel peppers if desired. In a large bowl, whisk together tomato, vinegar, salt and remaining 2 tablespoons oil. Scrape corn kernels, from ears into bowl. Cut peppers and mushrooms into 1/4-inch-thick slices, add to bowl. Cut squash into 1-inch lengths, halve onion slices, and add to bowl. Toss well to combine and serve. Or cover with plastic wrap, refrigerate and serve chilled.