Heat a large pot or Dutch oven over medium heat. Add the oil and allow it to heat for a minute, then add the diced onion. Stir and cook for 1 minute, to soften.
Add the diced carrots, ginger, and 1 teaspoon of salt. Stir to combine and cook until they start to soften, stirring occasionally (about 10 minutes).
Add the curry powder and cook for about 2 minutes, stirring occasionally.
Stir in broth and bring to a boil over medium-high heat. Then reduce the heat to medium-low and simmer until the carrots are softened, usually between 10–15 minutes.
Remove from heat and purée the soup using an immersion blender (or in batches using a standard blender, if you don't have an immersion).
Stir in the coconut milk and lime juice and season with salt to taste. I usually add about ½ tablespoon of kosher salt.
Serve with fresh cilantro, chopped peanuts, and a sprinkle of ground sumac.
