slice chicken into strips, combine with soy sauces, vinegar, and galangal powder to marinate while prepping remaining ingredients
Turn onion, garlic, and chili into a paste using a mortar and pestle (or a blender)
Fry onion, garlic, and chili mixture in oil for a minute or so until fragrant.
Add chicken including marinade to hot seasoned oil
Dissolve maggi cubes in water. Add to chicken along with ketchup and celery leaves
cook uncovered for 10-15 minutes or until the sauce has reduced to a thick slurry coating the chicken pieces.
Taste and season with salt/pepper/sambal oelek if desired. Cook for 1 more minute
Serve with cucumber salad and rice, or in bread rolls with sliced cucumber, fried onions, and perhaps some achar or similar pickle