Blanch the cauliflower florets in a large pan of boiling salted water, then drain and refresh in iced water.
Cook the yam in another large pan of boiling water for about 20 minutes, or until soft.
If you would like to smoke the yam, put a few small pieces of hot charcoal in a small heatproof bowl and place the bowl in a large, heavy-based pan. Arrange the boiled yam cubes around the bowl, then place the cardamom pods on the charcoal, pour on the ghee and, as the smoke bellows, cover with a lid and set aside for about 15 minutes.
Heat the ghee in a deep, heavy-based pan over medium heat, add the cumin seeds, and stir-fry for about 1 minute, or until they start to splutter. Add the onion, garlic, and ginger and stir-fry for about 2 minutes, or until the onion is translucent and glossy.
Add the cauliflower and smoked yam and stir-fry for 1 minute, before adding the kachri powder, coriander, chilli powder, turmeric, and amchoor.
Season with salt and stir-fry, adding 2 tablespoons water at frequent intervals, for about 5 minutes. Remove from the heat and adjust the seasoning, if necessary.