Cut the cauliflower into bite-size florets and soak them in a bowl of cold water for about 30 minutes. Drain.
Put the onion, ginger, garlic and 2 tablespoons water in a blender or food processor (I use an inexpensive mini processor for things like this) and blend until you have a liquidy paste.
Heat the oil in a large skillet or Dutch oven over medium-high heat, and sauté the cauliflower until you see a few golden spots, about 3-4 minutes. Remove to a plate.
Put the onion mixture in the same pan and and cook for 1 minute. The color will turn slightly golden.
Add the cumin, coriander and tomato sauce and cook for 2-3 minutes. Add the remaining ingredients (turmeric through salt) and stir well.
Add 1 1/2 tablespoons of water, stir again and reduce the heat to low. Add the cauliflower, cover and cook for 5-10 minutes or until cauliflower is cooked to your liking. (I cook on the lower side of this time frame as I like the cauliflower to be on the crisp side. Don’t hesitate to taste test after a few minutes to determine when it is cooked to your liking.)