Soak the Dried Long Red Chilies in hot water for 15–20 minutes until softened, then drain and reserve a little soaking liquid.
Toast the whole spices in a dry skillet over medium heat — Coriander Seeds, Cumin Seeds, White Peppercorns, a small stick of Cinnamon and a few Green Cardamom Pods — until fragrant, about 2–3 minutes. Grind them to a fine powder with a spice grinder or mortar and pestle.
In a blender or food processor combine the softened chilies, the toasted spice powder, peeled Shallots, peeled Garlic, peeled Fresh Turmeric (or turmeric powder if unavailable), sliced Fresh Ginger, and a teaspoon of Shrimp Paste. Add 1–2 teaspoons of Yellow Curry Powder, a splash of the reserved chili soaking liquid and a little Neutral Oil to help it blend, and process to a smooth paste.
Heat 2–3 tablespoons of the neutral oil in a heavy pot over medium heat. Fry the curry paste, stirring constantly, until it becomes fragrant and the oil begins to separate, about 4–6 minutes.
Stir in most of the Coconut Milk (reserve a little for garnish if you like), then add enough Chicken Stock to reach your desired soup consistency. Bring to a gentle simmer.
Add the Chicken Thighs to the simmering curry, reduce the heat to low, cover and poach until the chicken is tender and cooked through, about 20–30 minutes. Remove the chicken, shred or cut into bite-sized pieces, and return to the pot.
Taste and season the broth with Fish Sauce and Palm Sugar to balance salty and sweet — start with 1–2 tablespoons fish sauce and 1–2 teaspoons palm sugar and adjust to taste.
While the chicken simmers, cook the Fresh Yellow Egg Noodles in a pot of boiling water just until tender (usually 1–2 minutes), drain and rinse briefly under hot water to loosen. Set aside.
For the signature crunchy topping, heat a couple of inches of oil in a small pot or wok to hot but not smoking. Fry small nests or portions of the fresh noodles in batches until golden and crisp, about 1–2 minutes; drain on paper towels. (If you prefer, you can pan-fry a little oil in a skillet and crisp them that way.)
To assemble, divide the cooked noodles among bowls, ladle the hot coconut-curry and chicken over them, and top each bowl with a handful of the crispy fried noodles. Sprinkle with Thai Chili Flakes to taste, add chopped Pickled Mustard Greens, thinly sliced additional Shallots, a generous squeeze of Limes, and a scattering of Fresh Cilantro (Coriander) Leaves.
Finish with an extra drizzle of reserved coconut milk if you like and serve immediately so the crispy noodles stay crisp at the last minute.
