In a mixing bowl, whisk together the soy sauce, sesame oil, lime juice, garlic powder, ground ginger, and optional chili flakes until well blended. Add the boneless skinless chicken thighs, ensuring they're fully coated with the marinade. Cover the bowl and let it marinate in the refrigerator for 20 minutes, or up to 4 hours for deeper flavor.

While the chicken marinates, prepare the creamy peanut sauce. In a separate bowl, combine peanut butter, soy sauce, honey, rice vinegar, sesame oil, garlic, and ginger. Whisk until smooth, adjusting with warm water as needed.

In a large mixing bowl, toss together the shredded green and red cabbage, julienned carrots, diced red bell pepper, sliced scallions, and chopped cilantro. Dress with lime juice, rice vinegar, sugar, and a pinch of salt. Let sit for 10 minutes.

Heat a grill pan or large skillet over medium-high heat. Cook marinated chicken for 5-7 minutes on each side until cooked through, reaching an internal temperature of 165°F (75°C). Let it rest before slicing thinly.

Warm tortillas, spread peanut sauce on each, layer with slaw and sliced chicken, drizzle with more peanut sauce, roll tightly, and slice in half to serve.