Heat the oil in a saucepan. Test the heat by adding one cumin seed to the oil; if seed cracks right away, oil is ready. Add the asafetida and cumin seeds. When the cumin seeds crack, add the tomato puree, coriander powder, turmeric, and red chili powder. Cook three to four minutes on medium heat. The tomato mixture will separate from the oil and reduce to about half in quantity.