Cook the pasta according to package directions, reserving 3 tbsp. of the cooking water.
Meanwhile, in a medium bowl, whisk together the peanut butter, soy sauce, vinegar, and hot sauce. Add the chicken, carrots, scallions, cilantro, and salt, and toss to coat. Add the pasta shells and the reserved cooking water, and toss until evenly coated.
Trim off and discard the top of each pepper, then cut out the seeds and core. Without making a hole, cut a slice from the bottom so that the pepper will stand. Evenly distribute the filling among the peppers, mounding it. Sprinkle with more cilantro before serving.