Step 1

Place 1/4 cup mayonnaise or yogurt, 1 tablespoon freshly squeezed lemon juice, 1 teaspoon granulated sugar (optional), 1/2 teaspoon kosher salt, and 1/8 teaspoon black pepper in a large bowl and whisk to combine.

Step 2

Prepare the following, adding each to the bowl of dressing as you complete it: Core and dice 2 medium apples (about 2 cups, no need to peel); halve 2 stalks celery lengthwise, then thinly slice crosswise (about 1 cup); halve 1 cup seedless red grapes.

Step 3

Place 3/4 cup walnuts in a small skillet over medium heat. Cook, tossing frequently, until fragrant and lightly toasted, 2 to 3 minutes. Transfer to a cutting board to cool slightly, about 2 minutes. Coarsely chop, add to the salad, and toss to combine.

Step 4

Divide 12 lettuce leaves among 4 wide, shallow bowls or plates. Divide the salad evenly between the bowls. (Alternatively, coarsely chop the lettuce and toss with the salad.) Garnish with celery leaves and more black pepper.