Push vegetables aside. Add beaten eggs and scramble until set. Mix eggs with vegetables.
Add cooked rice, breaking up clumps. Stir-fry with vegetables and eggs. Add remaining soy sauce, oyster sauce (if using), and sesame oil. Season with salt and pepper.
Add cooked chicken back to skillet. Mix well and cook for 2-3 minutes to heat through.
Remove from heat. Sprinkle with chopped green onions and drizzle with Sriracha or chili sauce if desired. Serve hot.
Notes
For best results, use leftover rice that has dried out slightly. Customize with your favorite vegetables or add chili flakes for extra heat.