Chicken Banh Mi

2 carrots -- peeled and shredded
1/2 cucumber -- peeled, halved lengthwise, seeded, and sliced thin
1 teaspoon  lime zest
5 Tablespoons  lime juice
1/4 cup  fish sauce
3 Tablespoons  dark brown sugar -- packed
1 rotisserie chicken -- 
             (2 1/2-pound) skin and bones discarded, meat shredded into bite-size pieces (3 cups)
1/2 cup  mayonnaise
5 teaspoons  Sriracha sauce
4 sub rolls -- (8-inch) split lengthwise and toasted
1/2 cup  fresh cilantro leaves

1. Combine carrots, cucumber, 2 tablespoons lime juice, and 1 tablespoon fish sauce in bowl and let sit for 15 minutes. Combine sugar, remaining 3 tablespoons lime juice, and remaining 3 tablespoons fish sauce in large bowl and stir until sugar is dissolved. Add chicken and toss to coat. Whisk mayonnaise, Sriracha, and lime zest together in separate bowl.

2. Spread mayonnaise mixture on roll bottoms. Divide chicken mixture among rolls and top with pickled vegetables (leaving liquid in bowl), cilantro, and roll tops. Serve.