While the 54-year-old restaurant owner, Nguyen Thi Lien, knew that a foreign television crew was on the way to her restaurant she had no idea they would be bringing a very special guest along with them.
In an interview with AFP, she said: "His presence in our restaurant was a great surprise for my whole family, who could never have imagined it, even in our dreams."
The US Secret Service and the local police had closed down the streets surrounding Bun Cha Huong Lien eatery on Monday evening. A large crowd gathered outside the restaurant, letting out a cheer as Obama exited from the restaurant.
Before getting into his limousine, the US president stopped to greet excited locals while many of them captured the moment on their phones.
"Obama was nice, smiling, cheerful and popular with everyone," the shop's owner said, adding that she regretted not posing for a picture with the president.
Bourdain, who is renowned for his love of cheap streetside food, later tweeted, "Total cost of bun cha dinner with the President: $6.00. I picked up the check."
He also complimented Obama on his chopstick skills in an Instagram post, describing them as "on point."
Obama had arrived in Vietnam on Sunday as part of his tenth trip to Asia as the US president. The meal might have offered the American president a brief respite from his daunting schedule.
During the visit Obama announced the lifting of the decades-old arms import embargo on Vietnam.
Obama's restaurant visit will be featured in an upcoming episode of Bourdain's CNN programme 'Anthony Bourdain Parts Unknown'. The network said the programme would air in September.