Heat the oil in a medium Dutch oven or saucepan over medium heat. When hot, add the onion and cook for 5 minutes until softened and translucent. Add the carrots, garlic and ginger and cook for 5 minutes until the carrots are just beginning to soften and the garlic is fragrant. Add the sweet potatoes, five spice, salt and pepper and cook for 1 minute more.
Stir in the vegetable broth and bring to a boil. Lower to a simmer, cover, and cook for 30-35 minutes until the sweet potatoes are very tender when pierced with the tip of a sharp knife.
Now it’s time to purée the soup! You can do this with an immersion blender if you have one or using a regular blender. (If you use a regular blender, make sure you remove the cap in the lid, and plug that hole with a dishtowel before you start blending to prevent hot soup explosions.)
Return the soup to the pot. Taste and season with a little extra salt or cayenne if necessary.
Ladle the soup into bowls and garnish with fancy toppings of your choice.