Heat a heavy bottom pan or kadai adding all the seasoning ingredients in the order mentioned under "Seasoning ingredients" list.
When the mustard seeds start popping up, include finely chopped tomatoes. Add salt, turmeric powder, jaggery and red chilly powder. Saute well and let it cook in simmer.
Meanwhile heat a seasoning pan and dry roast fenugreek seeds and mustard seeds one after the other. Fenugreek seeds will turn brown and mustard seeds will pop up when they are rightly roasted.
Using mortar and pestle finely powder the roasted fenugreek and mustard together.
When the tomatoes are cooked completely to a mash-able consistency and thokku has started thickening, include the roasted fenugreek, mustard seed powder. Mix well. Switch off flame.
Tomato thokku is ready to be relished as side dish with rice, curd rice or dosa.
