In a medium bowl, combine 2 oz. cheese with vinegar and olive oil, using a fork to mash cheese. Season to taste with salt and pepper.
In another bowl, toss apples and endive with half the dressing, then divide evenly onto 4 plates. Crumble remaining 2 oz. cheese over each salad and top with walnuts, then drizzle with remaining dressing.
Note: Nutritional analysis is per serving.