The product is Vietnamese but the origin of the sauce comes from Thailand.
This sauce is produced by Huy Fong Foods, a California manufacturer. Created in 1980 by Vietnamese-American founder David Tran,[5] it is a brand of Sriracha sauce often also known as "rooster sauce", because of the rooster prominently featured on its label. Some cookbooks include recipes using it as their main condiment.
Firetalkers: Interview with David Tran of Huy Fong Foods, Inc., Makers of Sriracha “Rooster” Sauce | The Official Scott Roberts Website
A dish of stir-fried rice noodles is thought by some to have been introduced to the city of Ayutthaya during the time of the Ayutthaya Kingdom by Vietnamese traders. Pad Thai comes from Vietnam, where it is known as pho sao. The Vietnamese made this dish during the Ayutthaya period and much later, at the time of World War II, the Thais adapted its taste and called it Pad Thai.
Bangkok Post article
@Jlaw Thailand famous dish, Pad Thai is of Vietnamese origin.