Bring water to boil in a large stock pot. Add chicken breasts and salt and pepper to taste. Cook for about 20 minutes, remove chicken breasts with a strainer, and set aside to cool.
To the chicken water, add the red bell pepper strips and cook for 30 seconds. Add the spinach, cook for 30 seconds, and with a strainer, remove pepper and spinach to a medium-sized bowl. Set aside. Add noodles to the boiling liquid and cook for 3 minutes. Strain out noodles and add to spinach mixture in bowl. Transfer hot broth to a large heatproof container.
In the now-empty pan, add olive oil over medium-high heat. Add chopped shallots, curry paste, curry powder, turmeric, coriander and garlic. Saute 1 minute, stirring constantly, until fragrant. Add broth back into pan and bring just to a boil. Meanwhile, shred the cooked chicken into bite-size pieces.
Add coconut milk to the broth, reduce heat to medium, and cook 5 minutes. Add in the chicken, green onions, sugar and fish sauce; heat for 2 minutes. Add noodle and spinach mixture back into the stockpot. Stir in cilantro and crushed red pepper.
Squeeze two lime wedges over the soup and stir in. Adjust seasoning to taste and simmer for a final 5 minutes. Serve in individual bowls, topped with a lime wedge.