In a pan, heat up a little oil, add in the cumin seeds, and saute for 1-2 minutes, till the cumin seeds start crackling.
Then add the chopped ginger, garlic, and the slit green chilli, and saute for 3-5 minutes, till the ginger and garlic start getting lightly roasted, turning light red in color.
Next add in the chopped onions and salt, and saute till the onions get well roasted and turn light brown.
Then turn off the gas, and let the roast cool down a bit.
Once the roast has cooled down to about room temperature, grind it in a mixie, along with the boiled palak, tomato, and retained broth set aside earlier (which should also have cooled down to about room temperature by now), till it forms a smooth paste.
Pour the paste back in the same pan used earlier, add in the paneer cubes, and cover and cook on medium low flame for 3-5 minutes, or until you see a light boil. Then turn off the heat.
Serve hot with roti / naan.