You probably won't be tempted to taste a vegetable called 'corn smut', so let's use its Mexican name, huitlacoche (or cuitlacoche). It's a fungus that infects ears of corn - in other words, it's somewhat like a mushroom.
It's understandable why many farmers think of huitlacoche as a disgusting blight on their produce - the fungus is misshapen, grey and ugly. In Mexico, though, it's considered a delicacy. I've only tasted it once - at a Mexican restaurant in New York, where the huitlacoche was sauteed with corn and onion before being wrapped in a corn tortilla. Compared with the other food at this place, the taco wasn't cheap and the amount of huitlacoche in it was paltry, but the small quantity I did taste made me wish I could try more.
The flavour of huitlacoche is deep and earthy, tasting vaguely of corn. You probably won't find it fresh in Hong Kong (unless organic corn farmers in the New Territories are inadvertently growing it; if so, let's hope they're eating it and not throwing it away) but it is available in cans by mail order. The flavour of the canned stuff is said to be far inferior to that of the fresh, but that's true with most canned vegetables.
If you are lucky enough to have a supply of fresh huitlacoche, keep it simple. Saute sliced onion in a skillet with oil, minced garlic and a little sliced chilli. Add fresh corn kernels and the huitlacoche (chopped, if it's in large pieces). Sprinkle the ingredients with salt then cook for a few minutes. Drizzle in some cream and simmer until the liquid reduces and coats all the vegetables, then serve this with warm corn tortillas.