Cut cauliflower into bite-sized chunks and cut potatoes into 1-inch cubes.
In a large heavy pot place vegetable oil and turmeric, ginger, cayenne pepper, cumin, and coriander. Heat ingredients on a medium flame and sauté for 3 minutes.
Add tomatoes, potatoes, cauliflower, and salt. Stir to mix.
Add the water. Bring to a boil.
Cover and simmer over low heat for 30 minutes or until vegetables are tender.
Sprinkle with garam masala and garnish with fresh cilantro. Serve with rice.
Note: Garam masala is a mix of spices commonly used in Indian cooking. You can often find it in larger grocery stores and, of course, in Indian specialty shops.