Chop the tomatoes, potatoes, and cauliflower and keep them in separate piles.
Boil the chopped potatoes in water for about 5 minutes and drain.
Over fairly high-ish heat, heat the oil. Add the mustard seeds, cumin seeds, ginger, hing and coriander. Fry for a few minutes stirring constantly to prevent scorching.
Add the chopped tomatoes. Reduce heat to medium and keep stirring. Break the tomatoes up with a spoon a bit to encourage a sauce. Add the turmeric, salt and jalapeno.
When the tomatoes have disintegrated quite a bit into the oil and spices, add the drained potatoes and cauliflower.
Stir well to coat the vegetables in the spice mixture.
Cover and reduce heat if necessary to steam the veggies. I noticed that the cauliflower made a lot of broth in the bottom of the pan. I took the lid off at this point to allow the juice to reduce.
When the cauliflower is well cooked and not crunchy it's done. This is according to my taste. I liked tonight's meal especially well because the caulflower was very soft. To some, it may have been overcooked, so cook it how you like.