Heat the olive oil in a pot over medium-high heat. Add the onion, bell pepper and celery; cook, stirring, about 5 minutes. Add the garlic, curry powder, paprika, cayenne and 1 teaspoon salt; cook, stirring, 2 more minutes.
Add the tomatoes, chicken broth, brown sugar and 1 cup water to the pot, then whisk in the peanut butter until incorporated. Bring to a boil, then reduce the heat and simmer gently, stirring occasionally, until the soup thickens slightly, about 30 minutes. Puree with an immersion blender or in a regular blender in batches.Season with salt and black pepper.
Ladle the soup into bowls; top with creme fraiche, celery leaves, cilantro and peanuts. Drizzle with olive oil. Photograph by Con Poulos
When blending hot liquids, first let cool for 5 minutes or so, then transfer to a blender, filling only halfway. Put the lid on, leaving one corner open; Cover the lid with a kitchen towel to catch splatters and pulse until smooth.