Start by dicing the apples into bite-sized cubes, keeping the skin on for extra color and nutrients. Immediately toss them in a bowl with fresh lemon juice to prevent browning. I always make sure each piece is lightly coated so they stay fresh and vibrant.
Halve the grapes lengthwise for better texture and easier eating. Thinly slice the celery so it blends evenly throughout the salad without overpowering each bite. The thin cuts make every forkful balanced and crisp.
Place the walnuts in a dry skillet over medium heat and toast for about 3–5 minutes until fragrant. Stir frequently to prevent burning and allow them to cool before adding to the salad. Toasting deepens the flavor and keeps them crunchy.
In a separate bowl, whisk together the Greek yogurt, mayonnaise, Dijon mustard, honey (if using), salt, and pepper. Mix until smooth and creamy with no lumps. Taste and adjust seasoning based on your sweetness preference.
Add the grapes, celery, and toasted walnuts to the bowl of apples. Pour the dressing over the mixture and gently stir until everything is evenly coated. Be careful not to overmix so the fruit stays intact.
For the best flavor, refrigerate the salad for at least 30 minutes before serving. This resting time allows the flavors to meld beautifully. Serve chilled over crisp lettuce leaves for a classic presentation.