Preheat the oven to 350°F (175°C) and grease a 9x13-inch baking dish.
Make the sauce: in a medium saucepan combine sweet Thai chili sauce, soy sauce, dark brown sugar, peanut butter, tomato paste, pomegranate juice, rice vinegar, lime juice, fish sauce (if using), minced garlic, and grated ginger.
Bring the sauce to a boil over medium-high heat, then reduce heat and simmer, stirring occasionally, 10–15 minutes until slightly thickened; remove from heat and set aside.
In a medium bowl toss the shredded chicken with the sliced bell peppers, 1/2 cup of the shredded mozzarella, and about 3/4 cup of the sauce (just enough to coat the mixture).
Soften the tortillas by wrapping them in a damp paper towel and microwaving about 1 minute, or until pliable.
Divide the chicken mixture among the tortillas, spooning it down the center of each; tuck and roll each tortilla and place seam-side down in the prepared baking dish.
Pour the remaining sauce evenly over the assembled enchiladas, then sprinkle the remaining 1 cup of shredded mozzarella over the top.
Bake at 350°F (175°C) for about 30 minutes, until the cheese is melted and the dish is heated through.
Remove from the oven and top with sliced avocado, pomegranate arils, and chopped cilantro before serving.
