1. Slice the tomatoes, smear turmeric and salt on them and soak them in 1 cup vinegar. Leave for about 2 hours.
2. Blend together the garlic, ginger, red chilies and 3/4 of the mustard, with a little vinegar.
3. Heat the oil and add the remaining mustard. When the mustard crackles, add the fenugreek seeds.
4. Fry for 2 minutes and then add the blended mixture. Fry well for over 20 minutes.
5. Add the tomatoes and the remaining vinegar. Stir continuously as the mixture comes to a boil.
6. When the pickle is almost done, the oil begins to float at the top.
7. Take it off the heat and let it cool.

Store in a clean bottle. Will keep for a year.