I wouldn't be surprised if the secret ingredient to concocting a jet black burger that looks like it's been roasted on the flames of hell was one that inflicted a weeklong case of Montezuma's Revenge. But, somewhat ironically, these Satan's Especiales achieve their burnt & cursed aesthetic (whilst maintaining a soft chewy bun and succulent juicy beef patty) from medicinal charcoal, a mixture traditionally used to stop diarrhea.
Instructables contributor spunk began experimenting with the black burgers you see above after reading about a similar black food trend in Japan. Those who want to replicate the Hellfire Burgers...or maybe you'd prefer to think of them as Bat Burgers or Dark Knight Sliders...can get their full background, recipe, and cooking instructions here.
As for the black magic, follow the link below to get the burgers' requisite charcoal. spunk mentions having tried both charcoal tablets and charcoal powder, with a preference for the powder since it's easier to handle and cheaper to buy.
Note that charcoal can interfere with other medications, so be sure to look into which ones before you dig in or serve black burgers to guests. As previously mentioned it is also an anti-diarrheal. Meaning you might have some trouble making the other kind of dark matter if you eat too much of it. As a point of reference, spunk's burgers (yeah, spunk burgers, I know. Just be thankful that's not the secret ingredient) contain 1.25 grams of charcoal per serving. Dudes with the runs typically need to consume 1.5 to 4 grams to turn off the spigot.
Once you have the basic incorporation of charcoal into your food down, imagine the possibilities of edible blackness. Black mashed potatoes, black creme brulee, black chicken noodle soup, some big black cake for the ladies. All washed down with America's favorite pre-blackened potion: blk. bottled water.
Muchas danke to Foodiggity.