Preheat grill to medium high heat.
Season chicken with salt and pepper on both sides.
Lightly brush peach flesh with grape seed oil.
Place chicken on grill grates and grill each side for 5-7 minutes, or until chicken is no longer pink.
Place peaches on grill grates flesh side down. Grill for 3-4 minutes, or until there are grill marks.
Remove both chicken and peaches from grill and let rest.
To a small bowl add course ground mustard, dijon mustard, honey, apple cider vinegar, salt and pepper. Whisk to mix everything together. Set aside.
Assemble Salad: To a large bowl add spinach, blueberries, red onion, goat cheese, pecans. Slice chicken and peaches and top the salad. Serve with dressing on the side.