Mix: Combine peaches, red onion, tomatoes, cilantro, serrano, lime zest and juice, salt, and chili powder in a medium bowl.
3 fresh peaches, ½ cup red onion, ½ cup cherry tomatoes, ¼ cup fresh cilantro leaves, 1 small serrano chile, 1 lime, 1 tsp. kosher salt, ¼ tsp. chili powder