Peel and dice peaches and mangoes. Mince red onion and jalapeño. Rough chop cilantro. Add all ingredients to a large bowl and mix well. Best when chilled for 1 hour.
*While I prefer this salsa the day of, it is still great the next day. The onion flavor is more concentrated on day 2, so if you plan to wait to serve you might cut down on the onion.