Heat the olive oil in a large Dutch oven or large saucepan. Add the leeks and celery and sauté until the leeks begin to soften.
Add the garlic and dried herbs and sauté until fragrant.
Add the pumpkin, sweet potato and stock to the pot and stir to combine. Place the lid onto the pan and bring to the boil. Once boiling reduce to a gentle simmer.
Simmer until all of the pumpkin and sweet potato are soft and tender. At this point, remove the pan from the heat.
Carefully use an immersion blender to blend the soup in the pot. Alternatively, once cooled to room temperature, transfer to a heatproof blender or food processor and blend until smooth and creamy. Season with salt and pepper to taste.
Serve hot with your favourite bread and a drizzle of sour cream.
Notes
Storage
To freeze: Once cooled to room temperature, store in an airtight container or individual serving sized containers and freeze for up to 6 months. To refrigerate: Cool to room temperature and store in the fridge in the stock pot with the lid on. Refrigerate for up to 4-5 days.