How to Make It
In a medium saucepan, combine the vinegar, sugar, water, salt, ginger and star anise and bring to a boil over high heat. Add the watermelon rind and boil for 1 minute, then transfer to a heatproof bowl. Let cool, then refrigerate for 3 hours. Drain well and julienne the pickled rind.
In a large bowl, whisk the lime juice with the soy sauce, brown sugar, fish sauce, Sriracha, garlic and cilantro. Add the chicken to the marinade and turn to coat. Cover and refrigerate for 3 hours.
Light a grill and oil the grate. Remove the chicken from the marinade and season the thighs with salt and pepper. Grill over moderate heat, turning occasionally, until the skin is crispy and the chicken is cooked through, about 15 minutes. Transfer the chicken to a cutting board and let rest for 5 minutes.
In a large bowl, toss the julienned pickled watermelon rind with all of the ingredients except the lettuce leaves. Slice the chicken and serve in the lettuce leaves, topped with the slaw.