Set the sweet potatoes to cook in the microwave for 2 minutes. Pierce the skin a few times with a fork to make steam holes. This will get the cooking processes moving faster. The potatoes should not be mushy. Peel and slice into 1/2 inch rounds.
Heat oil in a large wok or frying pan over medium high heat. Add spices for about 30 seconds just to warm the flavors.
Add potatoes, cauliflower and water. Cover with a lid and let cook over medium-low heat, stirring occaisionally to prevent scorching.
Once the cauliflower is crisp-tender and the potatoes are soft, add the diced tomatoes and cook until they are warmed through.
Serve as a warm side dish to your favorite Indian foods.