- Place the lentils, fenugreek seeds and mustard seeds in a large saucepan, cover with 5 cm / 2-inches of water and leave to soak for about 1 hour until softened.
- Drain and rinse well in fresh cold water.
- Return the lentil mixture to the rinsed out saucepan, add the stock, bring to the boil stirring then reduce the heat, partially cover and simmer for about 30 minutes or until the lentils are soft.
- Meanwhile, heat the oil in a frying pan, add the garlic and onions and cook over a medium high heat, stirring, for about 5 minutes until lightly browned.
- Add onion mixture, crushed chile, carrots and celery to the lentils, mix well and continue to cook for a further 15 minutes or until carrots are tender.
- Allow the soup to cool a little then transfer to a food processor and process until pureed.
- You will probably have to do this in batches.
- Return the soup to the saucepan together with the salt, turmeric, curry powder and soy sauce.
- Mix well and simmer for 5 minutes.
- Serve hot.