The salad calls for herb salad mix, which can be found prebagged in the supermarket, or use any combination of lettuces and herbs. Any fresh cherry or berry (blackberries, blueberries, etc.) will do nicely. The dressing and caramelized walnuts can be made a day ahead (store the nuts in an airtight container and the dressing in the refrigerator).Adding fruits to a salad, whether it's blackberries, strawberries or blueberries, is a healthy way to eat something sweet that's filled with nutrients. Fruit is high in disease-fighting antioxidants and vitamin C, which boosts your immune system.