Dry roast the coriander and hulled black cardamom seeds, then grind them together in a spice/coffee grinder.
Peel and slice the ginger and tumeric. Pound together in the mortar and pestle.
Add the red curry paste and pound until the ginger and tumeric are fully incorporated. Then add the curry powder and ground coriander and black cardamom seeds. Again, pound until the curry paste is smooth and everything is incorporated.
To Make the Curry Soup:
Open a can of coconut milk and gently scoop the top layer of cream (~½ cup) into a large pot. Heat over medium high heat until you start to see an oily sheen. Add the khao soi curry paste and stir into the coconut cream. Cook until the curry paste has completely absorbed the coconut milk.
Then add the chicken drumsticks and coat in the curry paste.
Add the rest of the coconut milk, chicken broth, and water. Let boil gently (uncovered) for 45 minutes to an hour until the chicken is cooked through. The sauce will condense down and become rich during this time.
Season with palm sugar, light soy sauce, and dark soy sauce to taste.
To Make the Roast Chili Sauce:
Slice the garlic and shallots finely.
Heat a small pot of oil over medium heat.
Fry the garlic, shallots, and dried red chilis separately in this oil. Remove and save the oil.
Pound the fried garlic, shallots, and chilis together in the mortar and pestle. Add back 2 Tablespoons of the frying oil to form the chili sauce.
To Serve the Khao Soi:
Boil 12 ounces of egg noodles until they are al dente.
Fry the remaining 4 ounces of egg noodles in oil until golden brown.
Place the boiled noodles in the bottom of the bowl and scoop a chicken drumstick and the curry soup over the top. Top with a handful of fried noodles.
Serve with shallots, preserved mustard greens, lime slices, roast chili sauce, and a stalk or two of cilantro.