1. Preheat oven to 450 degrees F. Fit food processor with adjustable slicing blade. Using thick setting (6), slice potatoes. Toss potatoes with olive oil and season with ½ teaspoon salt and black pepper. Arrange slices on baking sheet in a single layer. Bake 20-25 minutes or until tender and beginning to caramelize; cool completely and refrigerate until ready to serve.
2. Meanwhile, adjust slice setting to thin (1 or 2), slice apple and celery; set aside. Fit food processor with mini-bowl and mini-multipurpose blade. Add walnuts, PULSE until coarsely chopped; remove and set aside. Add mayonnaise, green onion, lemon juice, sugar, remaining 1/2 teaspoon salt and cayenne pepper, if desired to mini-bowl; process until smooth. In large mixing bowl, combine apples, celery, dressing and half of the walnuts; toss gently until coated.
3. To serve, arrange arugula on individual salad plates. Top with roasted sweet potato slices, apple mixture and remaining walnuts. Serve immediately. Makes 6-8 servings
Recipe courtesy of KitchenAid