In a large, sturdy pot like a Dutch oven, melt butter over medium heat. Then add peeled and chopped carrots. Season with curry powder and salt and pepper. Cook until carrots soften and start to brown on the edges.
Add diced onions and cook for a minute or two. Then add about 2 cups of vegetable stock and use the liquid to scrape up any bits. Then add the rest of the stock and bring to a simmer.
Add coconut milk and simmer for 15 minutes.
Remove soup from the heat and let cool. Then blend until smooth (or use an immersion blender). Once smooth, return the soup to the heat.
Season the soup with salt and pepper and chili sauce. Serve garnished with cilantro.
For freezing: Cool soup completely and transfer to quart-sized freezer bags. Lay soup flat and freeze until solid. Reheat soup by thawing and then reheating in the stove top or on the microwave.