Wash tomatoes well, wipe them dry with a clean kitchen napkin. Dice into rough chunks.
Transfer to a thick bottomed pan, add red chilli powder and salt. Mix well. Cook covered on high flame for the first 5 minutes, then reduce the heat to medium-low, and let them cook covered for another 10 minutes, stirring occasionally. When the tomatoes have softened, and most of the water has evaporated, add in the cumin and coriander powder. Mix well and saute for another 2 minutes.
Switch off the heat, and set aside.
For the tempering - Heat oil in a skillet, add mustard seeds, when they splutter, add garlic, once the garlic has turned golden brown, switch off the heat and add curry leaves, red chillies, and asafoetida. When the curry leaves and red chillies turn crisp pour the tempering over the prepared tomato chutney and mix well. Enjoy with idli, dosa's etc. We enjoyed this with some delicious vermicelli idli's.