Palette-Swapped Alien Food

"''"This is for scene 23? You think they have apples on an alien planet?" "Why not? They speak English." "Look, get some kiwis, and spray-paint them red." "[pulls out script] Ok, so now it'll go "Nick walks into a garden of kiwi trees, says 'How like Eden this planet is,' and bites into a painted kiwi."''"

- Stargate SG-1, "Wormhole X-Treme!"

The culinary equivalent of Rubber Forehead Aliens. Alien cuisine has a suspicious tendency to look like Earth food ripped from its terrestrial context and subjected to food colouring—leading to things like green egg yolks, glow-in-the-dark yellow sauces, obsidian berries, and blue meat.

This rises from production considerations, of course. It takes time and energy to think up genuinely alien foodstuffs, and money to fabricate them—and in the end, the viewer might not even realize it's supposed to be food. By keeping the forms the same, creators can make it clear that a pudding is the ambassador's dinner and not, say, his wife; by shifting the palette, they retain a sense of otherworldliness.

The more humanoid the aliens in question, the more plausible this trope becomes. Green-skinned people who are shaped just like humans might very well share a biome with red-skinned vegetables that are shaped just like asparagus.

Anime and Manga

 * Tenchi Muyo! has beef bowls IN SPAAAAACEEE.

Film

 * Star Wars had BLUE MILK!
 * Morons From Outer Space mentioned a space beer that was green.

Live Action TV

 * The Red Dwarf episode "Legion".
 * Star Trek is fond of this:
 * Romulan Ale is blue.
 * TNG Gave us the Klingon specialities Gagh and Bloodwine
 * Parodied in Mad Magazine's spoof of The Wrath of Khan, which mentions "green wine" and "brown wine".
 * Shows up on occasion in Stargate SG-1. Lampshaded in the parody episode "Wormhole X-Treme!": "You think they have apples on an alien planet?... Look, get some kiwis, and spray-paint them red."
 * Babylon 5 has mostly normal food, but sometimes shows off alien food as well... and has at least one of the characters fail spectacularly in preparing it for another alien.
 * Showed up a lot in Farscape and also included non-human-looking utensils. According to the commentaries, sometimes they just used Asian foods that would look alien to the intended American audience.

Western Animation

 * In Lilo and Stitch, Jumba and Pleakly attempt to bait Stitch with what appears to be an ordinary chicken drumstick... which is also bright green, and covered in purple spots.

Real Life

 * Some genera of food plants have a relatively broad range of phenotype worldwide, but one particular form is dominant in a given region. And food preparation can vary in unexpected ways as well. So traveling to a different country, or just eating with people of a different ethnicity, may seem like this.
 * Probably the most famous case of this is the carrot, which originally came in a variety of colors ranging from white to red to purple. Orange carrots only became widespread after Dutch farmers during and after the Eighty Years' War bred their carrots that way to proclaim their support for the House of Orange (and thus Dutch nationalism). For whatever reason, the color spread and stuck.
 * And it is hardly unheard-of for chicken eggs to have moderately dark, greenish yolks, though commercially produced eggs in some countries tend to a brighter yellow. There are also breeds of chicken that consistently lay eggs with green shells. There are also blue, pink, gray, and probably others.
 * Various traditional preservation methods and processing techniques leave food looking, smelling and sometimes even tasting distinctly inedible because food only had to last. This is in contrast with modern food technology, which aims to modify taste and shelf life with as little cosmetic change as possible even if artificial means must be used. Corning beef will turn it an unappetizing gray color, but saltpetre can be added to the brine to preserve its reddish-pink color.