In a large Dutch oven or stock pot, add oil and heat over medium heat.
Then, add onion, celery and red bell pepper. Sauté for 2-3 minutes. Add garlic and sauté for 30 seconds.
Finally, add sweet potatoes, seasonings and vegetable stock and bring to a boil.
Next, reduce heat to low, cover and allow to simmer for 20-25 minutes, or until the sweet potatoes can be easily pierced with a fork.
When the sweet potatoes are cooked, remove from heat, and blend using an immersion blender, or transfer to a blender. Blend until all ingredients are smooth.
To finish, add coconut milk and stir. Serve warm.
In the Instant Pot:
Combine all ingredients except the coconut milk in a 6 or 8-quart pressure cooker.
Place lid onto pressure cooker and be sure the vent is set to seal.
Cook on high pressure for 10 minutes, then allow a natural vent for 5-10 minutes.
Uncover and use an Immersion blender to blend soup until smooth. If you do not have an immersion blender, you can use a regular blender to blend your soup.
Add coconut milk and serve warm.
Notes
Feel free to substitute chicken broth or chicken stock for the vegetable stock, and milk or cream for the coconut milk.