When a food truck strikes an item from its menu board, patrons are apt to write off the inconvenience as just another entertaining idiosyncrasy of eating far from a fixed kitchen. As Sean Mendes has learned since he earlier this month opened a permanent location of Roadside Seafood, it doesn’t work that way in restaurants.“People don’t expect you to run out of everything,” he says. “I’ve been doing three or four batches of she-crab soup.”The she-crab clamor is understandable, since Roadside – which got its start two years ago as a food truck – produces one of the city’s best bowls. Based on Mendes’ grandmother’s recipe, the soup bears little resemblance to the flavorless, overworked bowls of thick cream which have caused plenty of Charleston eaters to dismiss the dish as tourist pap. It’s almost more of a chowder than a bisque, crammed with picked crab and flecked with onion and celery.The soup is a carryover from the truck menu, along with the tacos, sandwiches and fried seafood baskets, but Mendes is looking to add a few more elaborate preparations, such as shrimp-and-grits and lobster mac-and-cheese.Mendes’ father is from Rhode Island, so Mendes is as fluent in lobsters and littlenecks as shrimp and softshells (which he’s putting on special this week.) The vinyl tablecloths in the spiffy dining room, which seats 40, are patterned with New England newspapers and lobsters.“I’ll eat anything that comes out of the ocean,” Mendes says.Roadside Seafood was Mendes’ solution to his local seafood disappointments: “What I wanted, I couldn’t find,” he says. “If I was wanting to go and get a crab cake, everything was imitation stuff or the portions weren’t right.” The truck was so successful that it frequently strayed from its parking spot at the True Value Hardware on Folly Road for various special events and catering gigs.“People over here were mad at us because we were never here,” says Mendes, who was also anxious to relocate his operations from a Duvall Catering kitchen.“How great would it be to have a home base 10 minutes from my house?,” he remembers asking himself when he realized the building at 807 Folly Road was available. Mendes says he used as many local suppliers as possible when designing the space, an approach which also guides his cooking. His spices come from Charleston Spice Company, and the bread’s baked by Ashley Bakery.The truck will continue to operate, but Mendes says the restaurant “is here to stay.”Roadside Seafood is open Tues.-Sat., 11 a.m.-9 p.m. and Sundays, 11 a.m.-7 p.m. The restaurant is closed on Mondays. For more information, call 754-5890 or visit facebook.com/RoadsideSeafood.