Heat the oil in a dutch oven over medium-high heat. Add the onion and carrot and cook, stirring occasionally, until onions start to brown, about 6 minutes.
Add the garlic, ginger, red pepper flakes, ½ tsp salt, and ¼ tsp pepper and stir to combine. Add the sweet potatoes and stir to coat. Pour in the vegetable broth and bring to a boil. Reduce heat to medium-low and simmer until potatoes are tender, about 15 minutes.
Working in batches, puree the soup in a blender until smooth. Return the pureed soup to the dutch oven over medium-low heat. Stir in the peanut butter and lime juice until fully incorporated and soup is heated through. Season with salt & pepper to taste.
Ladle into bowls and top with sliced green onion and chopped peanuts.
