In a dry skillet over medium heat, toast the chopped walnuts or pecans for a few minutes until they become fragrant and lightly golden. Keep a close eye on them to prevent burning. Remove from heat and let them cool before using. Make sure to let them cool before adding them to the salad to prevent wilting the arugula.
In a large salad bowl, combine the baby arugula, fresh blueberries, toasted chopped nuts, red onion slices, and dried cranberries.
In a small bowl, whisk together the olive oil, balsamic vinegar, maple syrup or agave nectar, salt, and pepper until well emulsified.
Drizzle the dressing over the salad and toss gently to coat the ingredients with the dressing.
Divide the salad into individual serving plates or bowls. Optionally, you can sprinkle extra fresh blueberries on top for an added burst of flavor and color.