Heat an 8-qt. pot of salted water over medium heat. Put chicken and potatoes in to poach when barely simmering. Continue to simmer until chicken is cooked through and potatoes are tender when pierced, about 15 minutes. Drain, then shred chicken.
Meanwhile, mix remaining ingredients in a large bowl. Add chicken and potatoes, tossing to combine.
Makes 10 cups (serving size: 1 cup)