I dislike the stuff, so I have cheerfully skipped it. I also use less oil than the original recipe calls for. Use even less if you so prefer. Try it, anyway. The potatoes should be a smallish, thin-skinned variety.
New potatoes are ideal.
If the skins are thin, leave them on. Heat the oil. Add the mustard, stir for a few seconds till the seeds pop. Add the kadi leaves. Stir a couple of times, then add the cauliflower, potatoes, peas, peppers, turmeric and salt.