Chop the onion, tomatoes, and chilies and give a couple pulses in a small food processor.
Heat 3-4 tablespoons of oil over medium heat, in a large frying pan.
Add the cumin seeds and saute until they brown and start to pop.
Add the garlic ginger paste (it will pop and spit!) and saute a minute.
Add the onion, tomatoes, chilies, and tumeric. Saute for about 5 minutes until it begins to brown.
Mix the amchoor powder, chili powder, ground coriander and water. Add to the pan along with a generous seasoning of salt and the and the kasoori methi (give the kasoori methi a bit of a rub in your palm to break down). Let saute for a couple minutes.
Add the cauliflower, tossing to mix. Drizzle with about 1/4 cup of water, put the lid on, and let cook for about 10 minutes. Stir to mix occasionally.
Sprinkle on the garam masala and a bit of salt. Toss to combine, and continue to cook, lid on, for anothe 5 minutes.