Heat oil in a medium saucepan until the oil is hot and just shimmering.
Add the pinch of asafetida if you are using, then add the 1 tsp cumin seed, 1 tsp black mustard seed, and let them pop for a second or two, then add the 2 bay leaves, the 1/2 tsp paprika, and 1/2 tsp turmeric.
Stir a few times then add the tomatoes, green chilies, and ginger.
Cover, let it come to a boil, then reduce heat to medium and let it cook for 5 - 10 minutes.
Add the cornstarch if you want the sauce to be a little thicker.
Add the sugar and cilantro if you are using.
Eat as is, serve with rice, lentils, bread, over a salad. Its use is only limited by your imagination.