To make the masterstock, place all ingredients in a pot and bring to boil. Reduce and simmer for 45 minutes.
Meanwhile shuck the abalone, prepare the choy sum, noodles and spring onions, and set aside.
Once the stock is ready, add the abalone and on cook on a low simmer for two hours. If not serving straight away, cool the abalone in the stock and place in the fridge overnight. To serve, reheat slowly.
Otherwise, remove abalone and slice thinly, allowing two abalone per portion. Also remove the shiitake from the masterstock, allowing three per serve.
In a large soup bowl add the softened noodles (hot) then add masterstock until it reaches halfway up the noodles. Place in the choy sum, mushrooms and then the abalone. Finally, add in more of the masterstock and finish with the sliced and julienned spring onions.