Woldorf Salad

Ingredients

• 6 tablespoons plain yogurt
• 1 tablespoon lemon juice
• 1/2 teaspoon kosher salt
• pinch of freshly ground black pepper
• 2 sweet apples, cored and chopped
• 1 cup seedless red grapes, halved, or 1/4 cup raisins
• 1 cup thinly sliced celery
• 1 cup chopped, slightly toasted walnuts
• lettuce