Put broth and chicken in a large pot. Bring to a boil, then reduce to a gentle simmer and cook until chicken is cooked through, about 20 minutes. Transfer to a plate and allow to cool. Skim broth.
Add corn and bell peppers to broth and bring to a boil, then reduce to a simmer and cook until peppers and corn are just tender, about 5 minutes. Meanwhile, remove skin and bones from chicken and shred meat into pieces.
Return shredded chicken to pot and stir in chile paste to taste and lemon juice. Ladle into bowls and sprinkle with parsley.
*Aji amarillo is a yellowish orange, fruity-hot chile from Peru. Find the paste at Latino markets.