Step 1: Pat chicken pieces dry with paper towels. In a medium bowl, toss the chicken with cornstarch, 1/4 teaspoon salt, and 1/8 teaspoon black pepper until each piece is evenly coated.
Step 2: Prepare the Bang Bang Sauce: In a small bowl, whisk together mayonnaise, sweet chili sauce, Sriracha (starting with 1 tablespoon and adding more for desired heat), and optional honey until completely smooth. Set aside.
Step 3: Fry the Chicken: Heat 1 cup of vegetable oil in a large skillet or wok over medium-high heat until it reaches 350-375°F (175-190°C). Carefully add chicken pieces in batches, without overcrowding the pan. Fry for 3-5 minutes per batch, until golden brown and cooked through. Remove with a slotted spoon and transfer to a paper towel-lined plate to drain excess oil.
Step 4: Coat Chicken: Once all chicken is fried, transfer it to a clean bowl. Gently toss the fried chicken with about half of the prepared Bang Bang sauce until evenly coated. Set aside.
Step 5: Start Fried Rice: Carefully pour out most of the oil from the skillet, leaving about 2 tablespoons. Heat the remaining oil over medium-high heat. Add the chopped onion and cook for 2-3 minutes until softened.
Step 6: Add Vegetables and Garlic: Stir in the frozen peas and carrots and minced garlic. Cook for another 1-2 minutes until fragrant.
Step 7: Scramble Egg: Push the vegetables to one side of the pan. Pour the whisked egg into the empty space and scramble until cooked through, then break it into small pieces and mix with the vegetables.
Step 8: Combine Rice and Seasonings: Add the day-old rice to the pan. Drizzle with soy sauce and sesame oil. Season with salt and pepper to taste. Stir-fry for 3-5 minutes, breaking up any clumps, until the rice is heated through and slightly crispy.
Step 9: Final Combination: Add the coated Bang Bang chicken to the fried rice mixture. Gently toss to combine all ingredients, ensuring the chicken is well distributed.
Step 10: Serve: Serve immediately, garnished with fresh chopped green onions and a sprinkle of sesame seeds. Offer the remaining Bang Bang sauce on the side for dipping or extra drizzle.