4 heads Belgian endive, sliced crosswise 1 inch thick (4 cups)
2 tart green apples, cored and thinly sliced
In a small bowl, whisk together sour cream, buttermilk, vinegar, honey, and scallion. Season with salt and pepper. In a large bowl, combine arugula, endive, and apples. Toss with dressing; serve immediately.