Zuko was wrong, actually. (I think.maybe.) Because juice, like, comes from the moisture in thing thing and then you remove the non-liquid bits, whereas in (most?) tea, you infuse the leaves with water instead of relying on the inherent water. True hot leaf juice would be if you extracted liquid from a couple leaves and heated it up, which would be expensive and probably bitter but a fun way to do it
Thank you, Professor Sokka
Boiling things in water in order to transfer flavor and other qualities into the water is, however, the standard way of making broth. Therefore, tea is just a very specific kind of vegetable soup.
Zuko: Welcome to Pao's Leaf Broths home of the world's weakest vegetable soup may I take your order
Uncle: *despair for his family intensifies*