For an extra layer of flavor, try toasting the walnut halves in a dry skillet over medium heat for 3-5 minutes before coating them in honey. If fresh blackberries are not available, you can use frozen blackberries that have been thawed and gently patted dry. The blackberry vinaigrette can be made ahead of time and stored in the refrigerator for up to 3 days. Just be sure to shake well before using. Feel free to customize the salad with other seasonal fruits and vegetables, such as pears, raspberries, or roasted beets.