Peel the butternut squash, remove the seeds, and cut into large cubes along with the carrots.

Heat the oil in a large pot or Dutch oven.

Add the chopped onion, garlic, and ginger to the pot and cook until softened, but not browned.

Add the cubed butternut squash, carrots, and lemongrass to the pot.

Cover the vegetables with vegetable stock.

Bring the mixture to a boil, then reduce the heat and simmer until the squash is tender (about 30-40 minutes).

Add the mango and chili pepper sometime during the last 15 minutes of cooking.

Remove the lemongrass chunks from the soup.

Stir in the coconut milk and curry powder.

Using a food processor or handheld blender, blend the soup until smooth and creamy.

Heat the soup again gently.

Season with salt and sugar to taste.