In large bowl, lightly toss together the diced apples, diced celery, finely chopped carrot and golden raisins until well mixed.
In a small bowl, whisk together the mayonnaise dressing, mustard, salt and black pepper until well blended.
Into a large skillet, pour enough water to reach a depth of 1 inch. Bring to a bare simmer. Add the sliced chicken breasts; gently poach until internal temperature of chicken registers 170°F on instant-read thermometer, 8 to 10 minutes. With tongs, remove chicken pieces from liquid to a plate. Let cool 5 minutes. Save cooking liquid for soup-making.
Meanwhile, in a small dry skillet, toast the curry powder over high heat, stirring occasionally, until fragrant, about 2 minutes. Stir toasted curry powder into mayonnaise mixture.
Cut the cooled chicken pieces into a small dice. Add the chicken along with the curry-mayonnaise mixture to the apple mixture; gently fold together with a rubber spatula until all the ingredients are evenly coated. Cover and refrigerate until serving time.
To serve, make sandwiches with the chicken salad, pumpernickel bread and lettuce.