For the Paste:
1 tablespoon citrus prickly ash (you can substitute Szechuan peppercorns for this)
2 tablespoons coriander seed
4 dried guajillo chilies (cut off tops and deseed)
1 tablespoon chopped peeled ginger
2 teaspoons of chopped peeled fresh turmeric (available at Asian markets)
4 shallots chopped
1 tablespoons of rock salt
2 teaspoons curry powder
1 1/2 cup thick coconut cream
4 chicken thighs
3 cups chicken broth
Palm sugar to taste (can use granulated sugar instead, palm sugar is available in Asian markets)
Fish sauce to taste (probably about 1/4 - 1/2 a cup)
2 tbsp of chopped cilantro
1 bag of fresh flat egg noodles (available at Asian markets or can be made fresh at home with an egg noodle recipe, cut on the linguini cutter of most pasta machines)
Toast all spices and chilies in a dry sauté pan over medium heat until fragrant and toasty. Toast turmeric and shallots in a separate dry sauté pan over medium heat until you start to see slight browning. At the restaurant, we pound all of the paste ingredients in a rock mortar and pestle until it’s a smooth paste, this is a long time consuming process, we enjoy the flavor this way and feel it’s more developed. In sake of saving time you can use a blender.
Once your paste is made you can start making the soup. Add 1 cup of thick coconut cream (this is not the same as coconut milk) cook this over low/medium heat until you start to see it separating. You will see a bit of grease forming on the top. You will then add the paste to this separated cream (this process is called cracking the cream). You will use the grease from the separated cream to fry the paste until fragrant and aromatic, be careful not to burn it.
Then we add the chicken thighs and fry them in the paste and coconut cream just until they start to brown. After you have browned the chicken thighs we add the remaining half cup of coconut cream and 3 cups of chicken broth. Stir to mix. Let simmer until chicken thighs are cooked through. Season the broth to taste with fish sauce and a touch of palm sugar.
With a large pot of boiling water boil the fresh noodles until the noodles are cooked. Strain the noodles into two large bowls.Top off with chicken thighs and the Khao Soi broth. Garnish with chopped cilantro.