Start by soaking the glass noodles in warm water for about 20-30 minutes or until they are soft. Once softened, drain them and set aside.
In a mixing bowl, combine the minced garlic, ground white pepper, sugar, oyster sauce, light and dark soy sauces, and sesame oil. Add the prawns and toss them gently in the marinade. Allow them to marinate for at least 15 minutes to absorb all the wonderful flavors.
In your steamer, place the soaked glass noodles at the bottom. Lay the marinated prawns on top of the noodles. Scatter the chopped spring onions, Chinese celery, sliced ginger, coriander roots, and crushed white peppercorns over the prawns.
Pour 200ml of water into the steamer and bring it to a gentle boil. Once boiling, place the steamer basket over the pot, cover, and steam for about 10-15 minutes, or until the prawns are pink and cooked through.
Carefully remove the steamer from heat. Transfer the prawns and noodles to a serving dish, making sure to drizzle any excess juices from the steamer over the top. Garnish with additional spring onions and coriander if desired.