In a covered large saucepan cook the onions, carrots, cilantro, ginger, garlic, and allspice in hot margarine for 10 to 12 minutes or until the vegetables are tender, stirring once or twice.
Transfer the mixture to a blender container or food processor bowl. Add 1/2 cup of the chicken broth. Cover and blend or process until nearly smooth.
In the same saucepan combine pumpkin, milk, and remaining broth. Stir in the blended vegetable mixture and the 8 ounces shrimp; heat through. If desired, on small skewers thread additional cooked shrimp. Ladle soup into soup bowls. If desired, top each serving with a spoonful of yogurt, a sprinkling of chives, and a shrimp skewer. Makes 4 servings.