Vietnamese food has been slowly inching its way closer and closer to the heart of Charleston. A few years ago, you had to drive out to James Island or North Chuck to enjoy pho and com ga don, and you found it amid the rattling of arcade skee-balls or under the flickering fluorescent lights of an Asian supermarket. Then pho started popping up on the peninsula on the narrow streets of Cannonborough, and banh mi sandwiches appeared under tents at the Marion Square market and in old warehouses beneath the Septima Clark overpass.

With the opening of CO at 340 King St., those classic street foods have finally arrived in style, moving into a new storefront location in the heart of the downtown shopping district.

CO’s single-page menu offers a sampling of traditional Vietnamese fare along with a few fusiony twists from neighboring countries. The “small dishes” section is perhaps the strongest, with 10 tempting appetizer-sized concoctions like a crispy pork and crab spring roll ($6) and a Vietnamese steak taco ($7) topped with “sri-rancha” dressing.

The pork belly buns ($6) pack a lot of flavor into a small package. The two steamed buns are soft and honey-sweet, and tucked inside is a piece of rich pork belly dressed with sweet hoisin sauce and a crisp slice of pickled cucumber. Add a dash of CO’s housemade sriracha for a flash of fire that contrasts nicely with the sweetness of the bun.

The pork and ginger gyoza ($5) are equally tasty. The tender dumplings have just a touch of golden brown sear around the edges, and inside is a savory minced pork mixture. The best part is the little ramekin of soy scallion sauce served alongside for dipping, which adds a nice sweet-and-salty boost to each tender bite.

The menu offers five varieties of banh mi, the Vietnamese baguette sandwiches that emerged from the French colonial period as a street food staple. CO’s fillings range from caramel pork with a fish and sugarcane marinade ($8) to shrimp in a sweet and spicy brandy sauce ($9). The five-spice pork belly ($9) sounds like it might be fiery hot, but it’s a fragrant, not spicy, blend of seasonings. The baguette is superb — firm but not too hard, crispy around the edges — and inside the silkiness of the thin-sliced pork belly blends perfectly with the acidic tang of pickled carrots and the crisp crunch from a long slice of cucumber, while a single thin strip of jalapeño adds just a hint of heat

For a heartier meal, there’s a selection of rice and noodle bowls, including pad Thai ($14) and Hanoi rice noodles with spicy yellow curry ($14), plus noodle soups like Vietnamese ramen ($12) with pork belly, shredded pork, and a poached egg in a savory pork broth.

CO’s pho ($12) is a fine version of Vietnam’s signature beef and noodle soup. The broth comes in a huge white bowl with wide folds of thin-sliced rare beef and strips of white onion already tucked away and warming inside. The bean sprouts, basil leaves, and sliced jalapeños served on the side are all fresh and ready enliven the broth, while the thick strands of vermicelli down in the bowl are tender and filling. Most important, the broth itself has a pleasing sheen of oily bubbles on the surface and is richly imbued with complex, savory flavors from long hours of simmering.

Even simpler entrées like the com chien ($14) are well-executed and tasty. A big, filling bowl of fried rice is tossed with egg, scallions, and a subtle lemongrass sauce, plus bits of pork, chicken, shrimp, and a mild red Shanghai sausage that’s tinged with a sweet accent.

There are vegetarian options on each section of the menu, too, including edamame dumpling ($5) and tofu bun ($6) appetizers to pad Thai ($14) or yakisoba ($13) tossed with tofu.

CO is located right in the thick of things on King Street. Owner Greg Bauer gutted the narrow two-story building and remade the interior, creating a space that’s stylish and elegant but with a funky, semi-industrial vibe. Downstairs there’s a long bar and a single community table, while upstairs is a mix of high and low two-tops flanked by three long picnic-style tables in a spare, minimalist wood-and-metal style. Old exposed brick walls are balanced by sleek black beams that support the sloping white ceiling, while panels painted with swirling red and white stripes add accents of bold color.

One should note that the food does take its sweet time coming, and CO, which bills itself as “banh mi — noodles — bar,” is more a place for relaxing and gabbing than dashing in for a quick bite. To help set the mood, there’s a full slate of beer, wine, and sake along with an ambitious cocktail list that includes East-West fusions like a gin and vodka martini ($9) laced with Thai basil leaves and lime or the blue bobba ($7) with vodka, coconut water, lemongrass syrup, and tapioca pearls.

All told, CO’s selection offers a pleasing array of bright, fresh flavors. Served in a sleek, high-energy environment with thumping dance music and a slate of clever cocktails, it’s a well-crafted formula that should help these time-tested Asian dishes appeal to a whole new crowd.