Boil pork belly in a medium saucepan for 15 minutes. Remove with tongs and allow it to cool. Cut into 1 inch strips.
Peel and cut bang kuang/jicama into matchsticks. Do the same for carrots. Slice cabbage as thinly as possible.
Cut off mushroom stems. Cut caps into thin slices.
Heat a wok or large fry pan. Add vegetable oil. Stir fry onion and garlic for 2 minutes.
Add pork belly, mushrooms, and cuttlefish. Fry for another 2 minutes.
Add bang kuang/jicama, carrots, and cabbage.
Then add dark soy sauce, salt, and pepper.
Continue to stir fry for 15 minutes until vegetables are soft. Sprinkle green onions on the top and transfer to a serving dish.