1. Keep the tomatoes, chopped onion and chopped potato in a pressure cooker and give them 3 whistles.
2. After it become cool, grind them in a mixer and make a puree of everything (tomatoes, onion, potato)
3. Put that on stove and boil it and add some salt and sugar and chili powder.
4. In a other stove keep a small vessel put the 2 tablespoon vegan butter and make it hot and after that put cumin seeds, turmeric powder and asafetida.
5. And give a Tadaka (mix the vegan butter in the soup) to the Soup which is in other vessel.
6. Again boil for some time and then put some chopped coriander and then serve hot.