First Lady Michelle Obama dined at Aquavit, the Scandi navian eatery on East 55th, as she continued her culinary tour of the city Tuesday. “She came by with a group of friends,” says a spy. “She was wearing a sleeveless black dress and had the tasting menu.” Obama tapped Aquavit chef Marcus Sam uelsson to cook last year’s state dinner at the White House for Indian Prime Minister Manmohan Singh. While on her spring break here, the first lady also stopped by Dinosaur Bar-B-Q in Harlem and Grimaldi’s pizzeria in Brooklyn.