Heat the chicken stock, add the agar agar shreds and stir over low heat until it melts. Strain and refrigerate until set.
Slightly smash the ginger slices with a knife to bring out the flavours. Place the ginger and the spring onion in the warm water. Rub with fingers to maximise the flavours until the water turns slightly green. Strain and reserve the water, discarding the solids.
Mix the chicken mince, sugar, soy sauce, cooking wine, sesame oil and pepper and stir well. Gradually mix in the cooled ginger water and stir well. Finely dice the set agar agar and add to the mixture. Stir well, cover and chill in the refrigerator at least 4 hours.
To make the buns, place the flour in a large bowl and gradually stir in the water and oil. Combine and knead to form a smooth dough. Cover with plastic wrap and let stand for 10 minutes.
Cut the dough into small balls, about 10g each. Roll them out into rounds. Spoon some of the mixture into the centre of each, draw up the sides to form a bag shape, and twist to seal. Place in steamers and steam over high heat for about 10 minutes or until cooked.