For the soup, heat the oil in a large saucepan. Add the garlic, onion, celery, ginger and salt and sweat over a gentle heat for 10-15 minutes, stirring occasionally, until the vegetables are soft.
Meanwhile, make the chutney. Blanch the carrot leaves in a pan of boiling water for 1 minute. Drain well and put in a small food processor. Add the remaining chutney ingredients, plus 1 tbsp water and whizz to a green sauce. Season and set aside.
Add the carrots to the soup and stir for a few minutes, then stir in the spices and sugar. Pour in 850ml water; add more salt if liked. Simmer for 10-15 minutes, until the carrots are soft.
Remove from the heat and, using a stick blender, whizz until smooth. Stir through the lemon juice and 3 tbsp crème fraîche. Mix the remaining 2 tbsp crème fraîche with the extra ¼ tsp ground cumin.
Divide the soup between bowls, add a blob each of cumin crème fraîche and chutney, then briefly swirl together. Serve with crusty bread, if liked.