Take a blender and put in the tomato to make a puree.
Now take another kadhai or a cooking pot and add mustard oil. Once the oil is hot, add the cumin seeds, bay leaf (break it from the middle), and a little hing (optional).
Stir them until a fragrance is released from the aromatics, and then add in the ginger paste.
Stir everything until the ginger turns a bit brown and the raw smell goes away.
Next, add the tomato puree and 2 green chili paste. Stir them really nicely and do it for around 5 minutes.
When the tomato puree starts to thicken, add the cumin powder, salt, and a bit of sugar.
Keep on stirring consistently.
Next, add in the turmeric powder.
Combine all the elements, and let them cook for a minute or two. Scrape from all the sides and stir occasionally.
When you see the oil has started to separate out a little from the masala, put in half a cup of water.
Cover the kadhai with a lid and let them shimmer on low flame for 5 minutes.