Grilling the peaches caramelizes their natural sugar. Serve with grilled pork, fish- like striped bass- or chicken. Refrigerate for up to 3 days.
Prepare grill to medium-high heat.
Lightly coat peaches and onion with cooking spray. Place peaches and onion on grill rack coated with cooking spray; grill peaches 2 minutes on each side. Cool and chop peaches.
Grill onion 3 minutes on each side. Cool and chop onion.
Combine peaches, onion, cilantro, and remaining ingredients in a medium bowl; toss well. Let stand 15 minutes.