Stir-fry the onions and garlic and pinch pepper and cook until golden, occasionally stirring for about 5 minutes. Add the carrots, garlic, ginger, lemongrass (optional), and apple cider vinegar, and then add 5 cups of broth. Reduce the heat to a simmer and cook until the carrots are soft, about 30 minutes.
Blend. Let cool slightly, transfer to a blender, add the coconut milk, and blend until smooth (about 1 minute). Taste and adjust salt and pepper, or even ginger, if you want it to be more gingery).
Serve with a drizzle of coconut milk, if desired.
Instant Pot Method
Stir-fry the onions, garlic, ginger, apple cider vinegar, and carrots in the instant pot using the stir-fry mode.
Add vegetable broth and close the lid. Set to pressure cook at high (204 C, 400 F) for 15 minutes. De-pressurize.
Blend. Let cool slightly, transfer to a blender, add the coconut milk, and blend until smooth (about 1 minute). Taste and adjust salt and pepper, or even ginger, if you want it to be more gingery).
Video
Notes
Feel free to add a cup of water if you want to dilute the flavor slightly or less stock to thicken the soup even more.