Remove and discard husks and silks from corn; set corn aside. Cut red pepper into quarters; remove and discard seeds and membrane. Brush corn and pepper quarters with 2 teaspoons oil.
Coat grill rack with cooking spray; place on grill over medium-hot coals (350° to 400°). Place corn on rack; grill, covered, 20 minutes or until tender, turning every 5 minutes. Let cool; cut corn from cob. Place red pepper on rack; grill, covered, 5 minutes on each side. Let cool; dice red pepper.
Combine corn, red pepper, onion, and remaining ingredients in a medium bowl; stir well. Serve at room temperature with chicken or pork or as a dip with no-oil baked tortilla chips.