Why is that about 90% of New York City street vendors — like this friendly fellow here — reply as such when asked for a knish? The reason is twofold. First, the knish has nosedived in quality over the last several decades, especially the type sold from carts. That’s brought demand for the knish way down. Second, health regulations changed. In 1996, pre-cooked potato was designated as a hazardous food item by the New York City health department. That meant that in order to be sold legally, any food containing cooked potato either had to be a) prepared on the spot just before serving, or b) held at a temperature of at least 140 until it was served. Since New York street knishes are fried, option “a” was out. I mean, try pushing an open vat of 375-degree fry oil down a sidewalk some afternoon. You’ll quickly see why the world isn’t full of mobile fish & chip stands. That left option “b”, but not every vending cart is equipped with the right sort of holding cabinet. Space is quite limited on a street cart — believe me, I know, I’ve sold from them before. It’s better not to take up space or add weight if you can help it, especially not for a slow-selling item like a mass-produced knish. Add all that up and you can see why the former king of the New York streets was long ago deposed by the pretzel and hot dog. Sure, there are still places to buy them, but the heyday of the knish is over.