In a large bowl, toss the apples, spinach, endive, walnuts, and blue cheese to combine. Advertisement In a small bowl, whisk together the vinegar, lemon juice, mustard, and honey. Add the oil in a thin stream, whisking to emulsify. Whisk in the salt and pepper. Pour the dressing on the salad and toss gently. Place the salad in a serving bowl and sprinkle with the chives.