Pre-heat oven to 350°F.
Using a small bowl, soak the red onion, carrots and radishes in ice water for 5 minutes; drain.
Split each roll in half lengthwise to make 4 pieces.
Transfer to the oven to toast.
In a large bowl, whisk 1/4 cup mayonnaise, lime juice, honey, cornichons, brine, and 1/2 teaspoon salt.
Add the chicken, onion, carrots, radishes and chopped cilantro; toss.
In a small bowl, mix the sriracha sauce and the remaining 1/4 cup mayonnaise.
Spread each piece of bread with Sriracha mayonnaise, then top with the chicken salad and cilantro leaves.
