Heat mustard oil and add ginger , cumin seeds, carom seeds, fenugreek seeds, onions seeds and mustard seeds and let it crackle.
Add chopped tomatoes with salt, cumin powder and chilli powder and cook on medium flame covered for 2-3 mins till they are soft.
Next add jaggery and tamarind and mix tomatoes well and keep cooking till all tomatoes are soft and mix well with jaggery and tamarind.
During winters when tomatoes are fresh, we get tangy ones too when using them for this chutney , tamarind isn't required.
Once its done mix it well with a laddle and let it cool and store in an air tight glass container for 5-6 days.