Prepare the Noodles: Cook the dried egg noodles according to package instructions until they are al dente, firm, yet tender. Drain them well and set aside, ready to soak up the flavors of the curry broth.

Prepare the Curry Base: Heat vegetable oil over medium heat in a large pot. Add red curry paste and stir-fry for 1-2 minutes until it becomes fragrant and releases aromatic oils.

Add Coconut Milk and Broth: Pour in the coconut milk and chicken or vegetable broth, stirring well to combine. Bring the mixture to a gentle simmer, melding the flavors into a rich, creamy base.

Season the Curry: Add soy sauce, fish sauce (if using), palm sugar, turmeric powder, and curry powder to the pot. Stir vigorously to dissolve the sugar and ensure even distribution of the spices. Taste and adjust seasoning with salt as needed to balance the flavors.

Cook the Chicken or Tofu: Carefully add the sliced chicken thighs or tofu to the simmering broth. Let them cook gently for 8-10 minutes, ensuring the chicken is thoroughly cooked, or the tofu is heated through and infused with the broth's flavors.

Assemble and Serve: Divide the cooked noodles evenly among serving bowls. Ladle the hot curry broth over the noodles, ensuring each bowl receives a generous amount of flavorful broth. Garnish each serving with a handful of fresh cilantro leaves and a sprinkling of crispy fried noodles for added texture and crunch.

Serve with Lime Wedges: Serve Khao Soi piping hot and lime wedges on the side. Squeezing fresh lime juice over the noodles just before eating adds a refreshing citrusy zing that enhances the dish's complexity and brightens the flavors.