Heat oil in a large saucepan. Add carrots and onions and fry 5 minutes.
Add garlic, ginger, curry and fry 2 more minutes. Add stock and lemon zest and bring to a boil. Reduce heat and simmer 20 minutes until carrots are soft.
Puree with a stick blender. Season with salt and pepper (and more ginger and curry powder if desired). Serve hot.