Combine all ingredients in a bowl. Whisk to incorporate. Add more water if it appears thick. Start with 2 tbsp Sriracha and add up to 2 more tbsp, to taste.
In a bowl, combine cabbage, carrots, chicken and Chow Mein. Top with peanuts, scallions and cilantro (optional), for garnishing.
Add 1/2 of the dressing, toss until evenly coated. Add more dressing, if you'd like. Serve.