In a pan, heat the oil and add the asafoetida powder and cumin seeds, let them splutter. Then add the garlic and green chillies and saute for a minute.
Once they start spluttering, add the tomatoes and chilly powder along with water that you can adjust as per your taste.
Now, add the jaggery powder, coriander powder, turmeric powder and salt in the pan. Cover with a lid, till the jaggery melts completely. Stir occasionally.
Once the jaggery is blended, add the thick sev and stir for a while. Let the concoction be on the liquid side, like gravy. The sev will absorb the water, but if you want the mixture to be on the gravy side you can add extra water.
The tomato sev sabzi is ready. Garnish with coriander leaves and serve hot with chapati or steamed rice.
