1. To prepare dressing, combine sherry vinegar, honey, and Dijon mustard in a small bowl; stir with a whisk. Gradually add olive oil, stirring with a whisk until blended. Add shallots, salt, and freshly ground black pepper; set aside.
2. Combine escarole and romaine lettuce in a large bowl. Add prunes and pecans, and toss well. Pour vinaigrette over salad; toss gently to coat. Serve immediately.