Heat olive oil in a large stockpot over medium heat. Add onion and cook for 5 min, until soft. Then add garlic, ginger, carrots, red curry paste, lemongrass paste, curry powder, garlic powder, salt, and brown sugar. Stir well and cook for another 5 min.
Add vegetable stock and coconut milk. Bring to a low boil, reduce heat, cover, and simmer for 30 min.
Remove from heat and add sour cream and lime juice. With an immersion blender, blend the soup until smooth. Cover and let rest for 15 min. Serve with chopped cilantro.