Fry mustard seeds and methi seeds seperately in a pan ( without any oil ) and powder them .
Cut lemons into small pieces,add salt to it and keep it in a dry vessel with lid for 3 to 4 days . Sundry it for 3 days by keeping muslin cloth on the vessel.
After 3 days add methi and mustard powder, dry red chilli powder to it and add salt . Heat oil and put a pinch of asafoetida and mix it in pickle . Cool it and Store in a dry bottle . Use a dry spoon for serving.
It will be very tasty with sour and hot flavour.