I have this headcanon that every time Zuko had a diplomatic visit, he would bring home some of the local fruits and ask the chef to make dessert from it. Then he would have it sent to Lady Mai, or if he can, he will arrange a private tea party with her.
Zuko definitely would enjoy reading her letters about the desserts and kept it like important informations, so can buy that fruit for her again. Or maybe he could try to sign a international trade contract (Mai definitely would call him insane, when he proudly showed her what he had done while they strolling through the market).
And when Mai was pregnant, she started to craving for very specific fruits and desserts that might not exist in their Nation. There were the time when the palace servants could spot the Fire Lord walking toward the Kitchen at midnight because his Lady suddenly wanted moon peach custard tart.
Cre of the middle picture:Viria



















