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