1 rotisserie chicken (about 2 1/2 pounds)
1 Granny Smith apple, cut into matchsticks
2 English cucumbers, cut into matchsticks
2 scallions (green parts only), thinly sliced
1/4 cup mayonnaise
3 tablespoons Dijon mustard
2 tablespoons cider vinegar
1/4 cup honey
Coarse salt and ground pepper
4 hamburger buns

Shred chicken, discarding skin. In a large skillet, heat chicken, mustard, vinegar, honey, and 1/4 cup water over medium-high, tossing to combine, until warmed through, 3 to 5 minutes; season with salt and pepper. Meanwhile, stir together apple, cucumbers, scallions, and mayonnaise. Divide chicken mixture among buns and top with apple-cucumber slaw.