In a large skillet over medium heat, combine the 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. Stir well until smooth and sugar has dissolved. Simmer for about 5 minutes to meld flavors.
Add shredded chicken and thinly sliced bell peppers to the skillet. Toss to coat in sauce. Cook an additional 3-4 minutes until peppers soften slightly.
Warm flour tortillas in a dry skillet or microwave to make pliable. Spoon chicken and pepper mixture into center of each tortilla, sprinkle with shredded mozzarella cheese, roll tightly, and place seam-side down in greased 9x13 baking dish.
Pour remaining sauce over enchiladas and sprinkle with remaining mozzarella cheese.
Preheat oven to 375°F (190°C). Cover baking dish with foil and bake for 20 minutes. Remove foil and bake an additional 10-15 minutes until cheese is bubbly and golden brown.
Remove from oven and let cool for a few minutes. Garnish with sliced avocado, pomegranate arils, and chopped cilantro before serving.