1. Combine the cabbage, carrot, and cauliflower in a medium-size saucepan. Add water to cover, and bring it to a boil over medium-high heat. Stir in the turmeric and curry leaves. Lower the heat to medium, cover the pan, and simmer, stirring occasionally, until the vegetables are fork-tender, 12 to 15 minutes.

2. While the vegetables are cooking, heat the oil in a small skillet over medium-high heat. Sprinkle in the split peas, lentils, coriander seeds, and chiles. Roast until the legumes and seeds turn reddish brown and the chiles blacken, 2 to 3 minutes. Using a slotted spoon, transfer the legume-spice blend to a blender jar, leaving as much oil in the skillet as possible.

3. Steal about 2 tablespoons of the cooking water from the simmering vegetables and pour it into a small bowl. Add the tamarind paste and stir to dissolve it. Pour this tart liquid over the spices in the blender jar, and add the tomato. Puree, scraping the inside of the jar as needed, to make a gritty, reddish-brown paste.

4. Drain the vegetables in a colander, reserving 1½ cups of the cooking water. Then return the vegetables to the saucepan. Add the lentil paste. Pour the reserved cooking water into the blender and give the blades a quick whir to wash out the jar. Add the washings to the pan, sprinkle in the salt, and stir once or twice.

5. Reheat the oil remaining in the skillet over medium-high heat. Add the mustard seeds, cover the skillet, and cook until the seeds have stopped popping (not unlike popcorn), about 30 seconds. Stir this seedy oil into the vegetables.

6. Heat the curry over medium heat, uncovered, stirring occasionally, to allow the flavors to marry, 3 to 5 minutes. Sprinkle the rice flour over the mixture and quickly stir it in. Cook until the curry has thickened, 1 to 2 minutes. Sprinkle with the cilantro, and serve.