Add onion, pineapple ring, garlic, pineapple juice in a blender. Blend into a puree then pour into a bowl.
Into the puree bowl, add sauce seasoning ingredients and mix well until well dissolved. Divide this sauce. Pour ½ the sauce to a quartz size ziplock bag and ½ the sauce into a gallon size bag. Fridge over night.
Chop chicken into 2"x2"chunks. Add chicken marinade and set aside for 5-10min.
Place the chicken into the gallon size ziplock bag with sauce seasoning. Message the sauce well into the chicken. Store in fridge for 2-3 hours to marinate.
Heat a cast iron pan on high and cook chicken. Control temp as needed. When chicken is half way done, pour in remaining seasoning sauce from quartz size ziplock bag. Stir well and keep cooking. When chicken is done, add in chopped pineapples and stir well. Turn off heat.
Serve meat in pan. Sprinkle perilla leaves, sesame oil and scallions. Enjoy!