Bánh, on the Upper West Side, is one of the city’s most reliable Vietnamese restaurants, a sunny, casual spot serving excellent renditions of crowd favorites, from enormous bánh mì to aromatic bowls of phở. A few months ago, after much anticipation, Bánh’s chef-owners, Nhu Ton and John Nguyen, expanded their footprint downtown, to the East Village, with the opening of Bánh Anh Em. Anh em is Vietnamese for “brothers,” and the two restaurants do have an unignorable shared DNA, but the new spot is decidedly more ambitious. The beef phở features the chewiest, springiest noodles, made fresh daily on an enormous, imported noodle-extruding machine whose retro-futuristic bulk crowds the space behind the bar. There, bánh-mì sandwiches are made on bread baked in-house—enormous, airy rugby balls of yeast and flour, with…