Add all the curry paste ingredients to a food processor and pulse until you get a smooth paste.
Heat oil in a large pot over medium high heat. Add 2 tablespoons vegetable oil and stir-fry the chicken until browned. Remove from the pot and set aside. To the fat left in the pot, add the paste. Fry for 3-5 minutes, until fragrant. Add the canned Thai red curry paste, broth, and brown sugar, and bring to a boil.
Reduce the heat to low. When the broth is at a low simmer, add the coconut milk and fish sauce. Add the chicken back to the broth.
Meanwhile, cook the noodles according to package instructions.
To serve, divide the noodles among 4 bowls. Cover with chicken and broth, and garnish with sliced shallots, lime wedges, pickled mustard greens, fried noodles, cilantro, and Thai chili paste.