To prepare the ingredients: Dry roast the fenugreek and crush into a powder. Soak the tamarind in about 100 ml water.
Pour vegetable oil into a pot, then add the roughly chopped tomatoes and cook.
The tomatoes should be cooked until soft (about 15 minutes). Oil will be added again at a later step.
In a separate pot, heat the vegetable oil, add the ingredients from the list from the mustard seed to the green chili peppers, and slowly cook. Add the garlic and sauté.
Add the curry leaf, then once cooked through, add the hing powder and turn off the heat. Add the soaking water from the tamarind (not the seed), the red chili powder, and salt, and turn on the heat again.
Add the spice mixture to the tomatoes, and slowly cook. Continue cooking until the oil separates. Discard any oil that separates out, if possible. Season with the fenugreek and salt to taste, and it's done!
Story Behind this Recipe
This is something my mother-in-law made for me for a long train ride. Since it was so delicious, I had her teach me the recipe.
The key is to continue simmering for a long time. I was told that the drained oil is good to use in dishes.