The Jasmine Dragon is a tea shop opened by Iroh in Ba Sing Se shortly after he and Zuko arrived in the city as refugees. After hearing about Iroh's brewing abilities, Quon, a merchant whose goal is to be the greatest tea baron in Ba Sing Se, visited the shop to see how good his tea was. More than satisfied, Quon offered to finance a tea shop for Iroh in the upper ring of the city. Iroh readily accepted, and he and Zuko were given an apartment in the upper ring of the city and ran it together. It was, however, very short-lived due to Zuko and Iroh's capture by Azula and the Dai Li.
After Aang defeated Ozai, Iroh liberated Ba Sing Se with the help of the Order of the White Lotus, Iroh reopened the Jasmine Dragon and served tea to the Avatar and his friends. He intends to spend his retirement serving tea now that the war is over. It is also here where the ending of the last episode of the series, "Sozin's Comet, Part 4: Avatar Aang", takes place.
BTW, best tea you'll ever have. Ever