This apple slaw with grape dressing tastes fresh and clean.
Heat oven to 350 degrees. Spread walnuts on baking pan. Bake until fragrant, about 10 minutes. Set walnuts aside to cool.
Place Concord grapes in the bowl of a food processor, and puree. Pass puree through a fine sieve set over a small bowl, and discard solids. Add walnut oil and lemon juice to the bowl, and whisk to combine. Season with salt and pepper; set grape dressing aside.
Fill a large bowl with cold water. Squeeze lemon halves into water; add rinds. Using a mandoline or a sharp knife, julienne apples. Place apples in acidulated water. Set aside.
When ready to serve, drain apples. Combine apples, green and red grapes, and dressing in a large bowl; toss gently to coat. Top with reserved toasted walnuts.
If Concord grapes are not available, substitute 1/4 cup Concord grape juice combined with 1/2 cup red grapes.