The make the filling, steam the pumpkin for 10 minutes or until a fork inserted shows little resistance.
Heat the rice bran oil in a frying pan on medium heat. Add the mushrooms, celery and carrots and stir-fry until the liquid from the mushrooms has evaporated. Add the five-spice bean cake and sauté for about 2 minutes.
Mash the cooked pumpkin into a paste. Add it to a medium mixing bowl along with the cooked vegetables. Mix in the soy sauce, sesame oil and pepper.
To make the broth, place the broth ingredients in a saucepan and bring it to a boil. Cover with a lid, reduce the heat to medium and let it simmer for 5 minutes. Briefly cook the bok choy in the broth, then set aside.
Bring a pot of water to the boil.
In the meantime, make the dumplings by placing 1 heaped teaspoon of filling in the centre of a wonton wrapper. Dip your index finger in a bowl of water and trace the edges of the wrapper with it. Fold the wonton wrapper in half to form a rectangular shape. Bring the two bottom corners together. Add a drop of water to those edges and press to seal. Repeat with the remaining filling and wrappers.
Cook the wontons on a low boil for 4 minutes or until cooked through. Drain.
Place the cooked dumplings and bok choy in a serving bowl, ladle over the broth, and garnish with the spring onion. Serve with the chilli oil as a dipping sauce.