BBQ Express has always seemed too good to be true — a shed in a Chinatown alley turning out cheap charcoal-grilled skewers? As is usually the case with Chinatown sidewalk sizzlers, the fish balls are so rubbery you could play stickball with them and the “Mexican corn” isn’t entirely authentic, but who cares? It’s a meat shack! Well, yesterday the Health Department put an end to the fun by slapping a closing order on it for “operating without a permit,” per the sign you see here. Here’s hoping this is just a paperwork problem and the smoke wafts across Mosco Street once again.