To prepare a tangy pumpkin soup with green chili swirl recipe, you'll first need to prepare your ingredients. Peel and slice your pumpkin. Cut the pumpkin in half lengthwise and scoop out the seeds. Place the flesh-side down on the bottom of the soup pot. Add the vegetable broth, pumpkin puree, and water. Bring to boil. Reduce the heat to medium-low and simmer until the vegetables are tender, about 30 minutes. Remove from heat and stir in the sour cream. Serve immediately.