Most books don't include foods that you can't find in the real world, but there are still numerous examples of foods that authors have created for their worlds over the years. Over the years, I've been able to amass a list of fictional foods that I wish I could try, and I imagine the cravings will stay with me for years, since there's no way I can create most of these.
Chocolate frogs from the Harry Potter series by J.K. Rowling. As far as fictional foods go, the wizarding world's food could form a list of its own. I'd try it all for the experience, even the cockroach clusters, but chocolate frogs hold the most draw for me. I would have chosen butterbeer, but I debated with myself whether drinks should count for this list and decided that they wouldn't. Plus, you can try butterbeer (and pumpkin juice) in the theme parks, studio tour, etc. that (in my mind at least) tastes a lot like "real" butterbeer (and is delicious).
Chocolate frogs are available in the theme parks as well, and I've had them along with the Harry Potter Alliance's chocolate frogs and a chocolate frog that was given to me by a woman cosplaying as McGonagall at LeakyCon 2011. They're good, as I would expect them to be, but it can't measure up to the experience of eating a real chocolate frog from the Harry Potter universe. We can make the butterbeer and the Bertie Bott's Every Flavour Beans (even if they contain less flavors) and whatnot, but we can't make chocolates that jump around like frogs. Without that, I'm never going to have the experience of eating a chocolate frog, even if I won't complain about getting any Muggle chocolate frogs either.
Fire flakes from Avatar: The Last Airbender. I have more questions about fire flakes than answers. Are they like potato chips, coconut flakes, or something else entirely? In my mind, they look like red coconut flakes, but I can't place their flavor other than "hot". We don't learn what they're made of other than "spices", so it's hard to pinpoint what you'd be eating.
The thing is, I don't like foods that are as spicy as these are implied to be. If this was a food available in grocery stores, I doubt I'd pay it much attention, but after being in my favorite TV show and being unavailable to me, it's created a curiosity that would lead to me buying them if given the chance. Even if I only took one bite and then was done with them forever.
Lembas from the Lord of the Rings trilogy by J.R.R. Tolkien. Who wouldn't enjoy the convenience of having lembas around? I certainly would. It's another one of those foods that we could try to imitate shallowly, but we'd never be able to re-create its magical properties.
Peeta's cheese buns from the Hunger Games trilogy by Suzanne Collins. This choice is different from the others in that we could make a good imitation of it in our world. I'm sure the ingredients are easy to find, and someone somewhere has probably made some of these that are exactly what Peeta was baking. Still, we don't know Peeta's exact recipe, and that's what I'm most curious about. These are Katniss' favorite, which only makes me want to try them more. (Plus, cheese and bread is always a nice combination.)
There are plenty of other fictional foods out there that people crave, whether its something that could never exist in our world or just a specific recipe that you know that you'll never be able to get. What fictional foods do you wish you had the opportunity to try?