Vietnamese pho is a category that rewards precision and patience, two things that were in short supply on the judging panel when Linh arrived at the Houston International Soup Festival. Her broth had been simmering for eighteen hours. The judges had been staring at the door for about forty minutes waiting for her to arrive. The official score sheet lists 'aroma' as the highest-rated category, which soup experts say is unusual and everyone else says makes complete sense.