Combine the leek, carrots, celery, garlic and 1/2 cup water in a medium saucepan. Cover and cook over medium heat, stirring occasionally, for 10 minutes or until the onion is tender.
Add the remaining 2 cups water, the chicken stock and the chicken. Bring to a simmer over medium heat. Reduce heat to low and cook, very gently, for a further 2–5 minutes or until the chicken is just tender. Remove the chicken from the soup with a slotted spoon and set aside.
Add the quinoa to the soup. Bring back to a simmer over high heat then reduce heat to medium and simmer for 10 minutes. Add the pumpkin and simmer for a further 5 minutes or until the pumpkin and quinoa are tender.
Meanwhile, use 2 forks or your fingers to shred the chicken. Add the chicken to the soup and heat through. Taste, season with salt and serve immediately sprinkled with the parsley
Quinoa is an excellent source of low GI carbs, fibre and complete protein, as well as being rich in B vitamins and minerals.