Whisk together 2 tablespoons soy sauce, 1 tablespoon sesame oil, 1 tablespoon lime juice, 1 teaspoon garlic powder, 1 teaspoon ground ginger, and 1/2 teaspoon chili flakes in a medium bowl. Add the chicken thighs and turn until completely coated. Marinate for at least 20 minutes at room temperature or up to 4 hours refrigerated.

Make the peanut sauce by combining 1/3 cup peanut butter, 2 tablespoons soy sauce, 1 tablespoon honey, 1 tablespoon rice vinegar, 1 teaspoon sesame oil, minced garlic, and grated ginger in a small bowl. Whisk until smooth. Add 1 to 2 tablespoons warm water gradually until sauce reaches pourable consistency that's thick enough to coat the back of a spoon.

In a large bowl, toss together the green cabbage, red cabbage, carrots, bell pepper, scallions, and cilantro. Add 1 tablespoon lime juice, 1 tablespoon rice vinegar, 1 teaspoon sugar, and a pinch of salt. Mix well and let sit for 10 minutes.

Heat a grill pan or large skillet over medium-high heat with a drizzle of oil. Cook the marinated chicken thighs for 5 to 7 minutes per side until golden brown and internal temperature reaches 165°F. Let rest for 5 minutes, then slice thinly against the grain.

Warm tortillas briefly in a dry skillet or microwave for 15 to 20 seconds. Lay each tortilla flat and spread peanut sauce down the center. Layer with slaw and sliced chicken, being careful not to overfill. Drizzle extra peanut sauce on top and add cilantro and chopped peanuts if desired. Fold sides in and roll from bottom to top like a burrito. Slice in half diagonally to serve.