HANOI -- In May 2016, U.S. President Barack Obama visited Vietnam to strengthen bilateral cooperation and lift a long-standing arms embargo. But it was a different part of his visit that captured public imagination. During the trip, he sat down with American celebrity chef Anthony Bourdain for dinner at Bun Cha Huong Lien, a family-run restaurant known for its grilled pork and noodles, which was filmed as part of Bourdain's television show "Parts Unknown."