Basic balti sauce

4 tbsps vegetable oil
2 spanish onions, chopped
3 garlic cloves, chopped
2 tbsps finely chopped ginger
4 green chillies, chopped
seeds from 10 cardamon pods
1 tbsp ground corriander
1 tbsp paprika
1 tbsp ground cinamon
1 tbsp ground tumeric
2 tsps ground cumin
1tsp ground fenugreek
1 tsp mustard powder
14 oz can chopped tomatoes
1 pt vegetable stock
2 tbsps lemon juice
pared rind of 1 lemon

1. Heat the oil in a heavy pan and fry the onions, garlic and ginger for 5 mins. Add the chillis and cook for 2 mins more.
2. Add the remaining spices then stir for 30 secs. Stir in the tomatoes, stock, lemon juice and rind. Bring to the boil then simmer uncovered for 30 mins.
3. Discard the lemon rind. The sauce is now ready to use or may be kept in a fridge for several days.