Mixed potato curry soup

In the best tradition of making it up as you go along... here's today's made up 'use the things you find in the cupboard before going to do the weekly shopping' soup...

1 leek, sliced
1 stick of celery, chopped
1 clove garlic, crushed
1 tbsp olive oil
Mixed spices approx 1/2 tsp of each - cumin seeds, turmeric, ground coriander, garam masala
2 potatoes, peeled and cut into smallish chunks
2 sweet potatoes, ditto potatoes
1 can chick peas, drained and rinsed
2 1/2 pints of vegetable stock
1 small bunch fresh coriander / 1/2 tbsp coriander paste (optional)

1. Prepare the vegetables
2. Heat the oil, add the celery, leek and garlic to a large pan and sweat until soft
3. Add the spices and stir for approx 1 minute
4. Add the potatoes, sweet potatoes and chick peas and stir into the leek and spice mixture
5. Pour in the vegetable stock, bring to the boil, then simmer for approx 40 minutes or until vegetables are soft
6. Use a food processor / hand blender to purée the soup
7. Return to the heat for five minutes, season to taste, stir in some fresh coriander and serve