Roughly cut the onions, ginger, garlic cloves, and tomatoes.
Take a kadhai or a cooking pot and add some oil. Let the oil heat until it starts smoking.
To this add the cumin seeds.
Stir for a few seconds until it crackles and then add the ginger and garlic.
Next, put in the onions and tomatoes.
Stir and fry them for a minute or so. Turn off the flame and let it cool down completely.
Now, take a blender and add the onions, tomatoes, ginger, garlic, and green chilis (break them from the middle) along with the soaked cashew nuts.
Make a fine creamy paste and keep it aside.