Heat the oil in a pan or kadai.
Add the mustard seeds, Jeera seeds and Asafoetida and allow to splutter.
Add the cut Tomatoes and salt. Allow the Tomatoes to be done till soft.
Add the Red chilli powder and heat the mixture on a low flame till the raw smell of the chilli powder goes.
Remove off the flame and preserve in air tight bottles.
This can be preserved for a maximum of 1 week. You could add preheated oil to this pickle to retain it for a long time. Time Taken apart from the initial preparations is approx. 20 minutes.