Roast duck

Roast Duck is a very common dish, eaten by the Earth Kingdom and Fire Nation. The Fire Nation eats it in a bowl cut into tiny pieces, while the Earth Kingdom eats it with a special sauce. Roast duck was first introduced in "The Boy in the Iceberg", when Iroh told Zuko he'll teach him advanced Firebending techniques after he finishes his bowl of roast duck. It was seen once more in "The Cave of Two Lovers", when Song and her mother served it to Zuko and Iroh after Iroh accidently poisoned himself.

As it can be assumed, Iroh is a big fan of roast duck, accepting Song's invitation to her house almost immeadiately when she mentioned her mother would always make too much of it.