Peel the prawn and separate the prawn heads for the soup. Chopped the prawn coarsely, mixed with the one teaspoon of candlenut powder and set aside. Heat up the frying pan, put a spoon of vegetable oil, brown the shallots and garlic, put in the prawn and toss until the prawn is cooked evenly, and put a few drops of soy sauce and salt to taste. Divide into 2 portion and set aside.
Boil the prawn head and galangal in a pot and strain to separate the soup, this will be the base of the soup, lower the heat.
Grind candlenuts, shallots, galangal and coriander powder into a fine paste.
Heat frying pan on medium flame, add vegetable oil.
Cook paste until quite toasted.
Pour the paste into the pot with prawn stock.
Pour half of the prawn paste into the pot as well
Slowly add the potato starch to the stock until the soup thicken till a gravy-like consistency is reached
Add salt, soy sauce to taste, pour the dark soy sauce until the soup colour is brown
decrease the heat to low, simmer gently 8 to10 minutes, add more potato starch if gravy is too thin or more water if the gravy is too thick, keep gravy hot on the low-medium heat, for serving.
Preparing the noodle
Take an another pot, pour about 6 cups water, bring it to a boil and lower the heat, put a serving portion of noodles in the sieve, dunk in the water briefly to warm up and top it on the bean sprouts. (if you want the bean sprout cooked, blanch it first in the boil water)
Ladle piping warm gravy over noodles.
Top with a little of each garnishing, and put a table spoon of prawn paste, serve while hot.