“Hem” means “alley,” and at this Asiatown spot you’ll feel as if you’ve been transported to Vietnamese street-food heaven. Out on the sidewalk, teens happily gather around kid-size tables; inside, the dining room enchants with details like weathered brick, birdcage chandeliers, a vintage Vespa, and even a tiny Italian Lambro three-wheeled truck. Much of the adventurous menu skews toward shellfish (though you must start with the garlic butter–drenched chicken cartilage). Our platter of grilled seafood featured oysters, clams, whelks, scallops, and mussels, all fresh and vibrantly sauced. The Grilled Skewers Combo offered sizzling beef, pork, okra, and chicken (hearts and gizzards).