The Vietnamese stretch of Argyle Street has seen better days. Take a stroll after sundown and it can seem downright intimidating, with storefront after storefront shuttered and nobody daring to tread into the dark beyond Tank Noodle (which, frankly, hasn’t been up to snuff lately either). Maybe that’s why more people didn’t notice back in October when a new restaurant opened on the corner of Argyle and Kenmore, the former home of Anh Linn Seafood, and prior to that the only place in town you could get butter-fried bear meat.