1. Combine arugula, spinach, and onion in a large bowl.
2. Combine juice, mustard, honey, salt, black pepper, and garlic in a medium bowl, stirring with a whisk. Gradually drizzle in olive oil, stirring constantly with a whisk. Drizzle dressing over salad, and toss gently to coat. Arrange 1 1/2 cups salad on each of 4 salad plates. Top each serving with 1/4 cup cherries, 1 tablespoon cheese, and 1 tablespoon nuts.