Melt margarine in a Dutch oven over medium heat. Add onion; sauté 3 minutes. Add sage, curry powder, and nutmeg; cook 30 seconds. Stir in flour; cook 30 seconds. Add broth, tomato paste, and salt, stirring well with a whisk. Stir in pumpkin and apple; bring to a boil. Cover, reduce heat, and simmer 25 minutes or until pumpkin is tender, stirring occasionally. Remove from heat; cool slightly.
Place mixture in a blender or food processor; process until smooth. Return mixture to Dutch oven; add milk. Cook until thoroughly heated. Garnish with sage sprigs, if desired.