Coat corn and peppers with cooking spray.
Grill corn and peppers, covered with grill lid, over medium-high heat (350° to 400°) 10 minutes or until vegetables are lightly charred, turning occasionally. Cool slightly.
Cut corn kernels from cobs. Remove stems and seeds from roasted peppers, and coarsely chop.
Stir together olive oil and next 5 ingredients in a large bowl; add corn, chopped pepper, avocado, onion, and cilantro, tossing gently to coat.