Stir together first 5 ingredients in a small bowl. Combine chicken and 1 tablespoon spice mixture in a medium bowl, and toss to coat. Set aside remaining spice mixture.
Heat olive oil in a large soup pot over medium heat; add chicken and cook, stirring often, 5 minutes or until no longer pink. Transfer to a plate.
Add onion, bell pepper, and jalapeño to soup pot; cook over medium heat, stirring often, 5 minutes or until vegetables are softened. Stir in garlic and reserved spice mixture; cook, stirring constantly, 1 minute.
Add pumpkin and next 5 ingredients to soup pot. Bring soup to a boil, reduce heat, and simmer, covered, 25 minutes or until pumpkin is tender. Return chicken to pot; simmer 2 minutes or until heated through. Remove from heat, and stir in lime juice. Garnish, if desired. Will keep, covered in refrigerator, up to 3 days.