Verbatim from the cookbook (I didn't follow it 100% - used less oil and more garlic and spices):
What you need:
1 large onion, chopped
2 tbsp sunflower oil
1 tsp curry powder
1 fat clove garlic, crushed
1 kg peeled and diced pumpkin
5 cups chicken or vegetable stock
1/2 - 1 cup buttermilk or coconut milk
1 400 g can copped tomatoes
salt and pepper to taste
Gently cook the onion in the oil with some salt (if desired) until softened but not browned. Stir in the curry powder and garlic, then add the diced pumpkin, cover and cook for about 10 minutes. Pour in the stock, cover and simmer for about 30 minutes or until pumpkin is tender.
Purée with an electric hand blender until smooth. If serving cold, add enough buttermilk to make a suitable consistency. Stir in the tomatoes but do not purée. Check the seasonings and refrigerate.
If serving hot, reheat gently with coconut milk, and add the tomatoes. Check seasoning.
Garnish with a sprinkle of garam masala and chopped coriander leaves. Serve with poppadums.