Secret Ingredient

Have you ever noticed how Auntie Alice's food always tastes so much better than anyone else's? It might be simply because Alice is a better cook, but it might be because of a Secret Ingredient she uses.

Truth in Television, as many chefs will keep part of their recipes secret.

This is a sister trope to And Some Other Stuff (when the secret ingredient is explosive rather than tasty). For unappealing versions, see I Ate What? and The Secret of Long Pork Pies.

Comic Books

 * In a Donald Duck comic book story, he insisted on putting ketchup on all of Daisy's cooking, much to her annoyance, because it just didn't taste as good as Grandma Duck's food. When Daisy checks with Grandma, it turns out the old lady's secret ingredient is...ketchup, which she puts in everything.

Film

 * Invoked but ultimately averted with the "Secret Ingredient Soup" in Kung Fu Panda: Po's (adoptive) father eventually reveals that there is no "secret ingredient" apart from its maker's skill.
 * Ed's secret sauce from Good Burger.
 * In Demolition Man John Spartan eats a burger made in the underground sewers by the people that live there. He keeps saying how great it is and then is told they are rat burgers. Most people would be disgusted, but he just keeps on eating it.

Literature

 * Superman - Last Son of Krypton. Clark Kent makes a bet with his rival Steve Lombard that his mother's (Mrs. Kent's) soft drink was the best drink ever. While on the planet Oric, he obtains a spice so powerful that a drop of it added to his mother's drink would make it irresistible to the human palate.

Live-Action TV

 * Cake Boss: Buddy has ordered the cameraman to stop filming a couple times, so Buddy can add a secret ingredient without the show's viewers learning what it is.
 * On Angel, Angel once drinks a cup of blood with an unusual taste. He's told "the secret ingredient is otter."
 * Reversed on Iron Chef, where the ingredient is a secret from the chef, not a secret of the chef's.
 * Same situation on Chopped.
 * Buffy the Vampire Slayer:
 * In "Doublemeat Palace" there's much talk of the secret ingredient in the Doublemeat Burgers. Buffy starts to suspect that it's the fast food workers themselves.
 * Played for laughs in "Conviction". When Angel's new secretary - Harmony - brings him blood that he finds tasty, she tells him the secret ingredient is otter blood.

Tabletop Games

 * Played with in one of the "Grimtooth's Traps" books. A butcher shop's offerings have a "mysterious and forbidden flavor". If the adventuring party takes the wrong exit after lunch, they end up on the menu—the unlabeled "meat" is from other dungeon delvers who walked into the processing department.

Video Games

 * Played with in Tales of Vesperia during the following skit where Yuri talks about his "secret ingredient". But gets averted hard by Rita's skit, when she threatens to use her own secret ingredient!
 * In the Korean Folktown arc in Maple Story, one part sees the town's baker - who makes excellent rice cakes, even though her grandson refuses to eat them - troubled by a mean Hogul (sort of a tiger-man Yokai) who threatens to eat her unless she gives him all the cakes. (He's been possessed by the Stone of Gluttony.) The player tries using the Radish Cure treatment - as in, giving him rice cakes until he gets sick, and hopefully vomits up the Stone - but this makes him want more and more. Finally, the baker has to make more cakes before he'll go away, and it's revealed what the "secret" is: not only does she not wash her hands before baking, she's never washed them at all. (This is why her grandson won't eat them.) It does the job, making the Hogul sick enough to purge the Stone, but the baker and her grandson have to relocate once the secret gets out.

Western Animation
"Grunka-Lunkas: Grunka lunka dunkity dasis, The secret of Slurm's on a need-to-know basis."
 * In Phineas and Ferb ("Meatloaf Surprise"), the secret ingredient in the Doofenshmirtz family meatloaf recipe is hate. "Usually it's love, but Great-Grandma Gretel had some issues."
 * In Courage the Cowardly Dog, the secret ingredient in all of Muriel's cooking is vinegar.
 * In an episode of The Proud Family Suga Mama's cooking is so delicious because she put her foot in it. Normally this is just a turn of phrase, but she meant it literally, and revealed it on a national TV show which caused everyone to get sick.
 * Arthur: Arthur & Buster enter a cooking competition and bake a cake; their secret ingredient is double the amount of chocolate the recipe calls for. Then DW accidentally uses up all the baking powder.
 * Futurama, "The 30% Iron Chef": After Bender wins a cooking competition using drops from a crystal flask filled with "the essence of pure flavor", Professor Farnsworth runs a chemical analysis and announces the mystery liquid is "Water! Ordinary water!" Immediately after Fry concludes that all Bender needed to cook well was confidence, the professor adds, "Yes, ordinary water, "
 * Also the secret ingredient of Slurm is.

""Sugar! Spice! And everything Nice! These were the ingredients chosen to create the perfect little girls. But Professor Utonium accidentally added an extra ingredient to the concoction... Chemical X. Thus, the Powerpuff Girls were born!""
 * At the end of the Back at the Barnyard episode, "Chez Pig", all of the barnyard animals ask Pig for the secret ingredient of his grandma's Truffle Pies, Pig finally gives in but when he reveals the secret ingredient, a duck shows up and quacks, completely drowning out what Pig said. However, the other animals are heard exclaiming in disgust, implying that the secret ingredient was actually disgusting.
 * The opening narration of The Powerpuff Girls:


 * In The Simpsons:
 * Marge's secret ingredient for pork chops is salt.
 * The secret ingredient for making a Flaming Homer cocktail is "Krusty Brand Non-Narkotik Kough Syrup".
 * The "secret sauce" at the Krustyburger has no secret ingredient, its actually mayonnaise that's been left out in the sun all day. (Yuck.)
 * Plankton's schemes in SpongeBob SquarePants revolve entirely around discovering the secret ingredient of the Krabby Patty at business rival Mr. Krabs' The Krusty Krab. At one point (after overtaking the restaurant with the help of his millions of hillbilly brethren), Plankton finds out that the secret ingredient is actual plankton (Plankton and his family do not take the news well), but Mr. Krabs reveals that it wasn't the real secret ingredient, just a fake one used to dupe Plankton. Another episode involves the entire restaurant going into lockdown as the secret ingredient is air-lifted in.
 * When Johnny Bravo wins a trip to the factory where they make Jake's Jerky, he sees his friend disappear into the vat labeled "Secret Ingredient," not realizing that his friend was only investigating it for himself. He then bursts into a press conference shouting, "Jake's Jerky is people!"
 * From Pinky and The Brain, one of the duo's nutty schemes to Take Over the World involves special Crêpes Suzette which explode like bombs when lit on fire (flambe-style) and the secret ingredient is added - nutmeg.

Real Life

 * Truth in Television. Just a pinch of the right herb or spice can work wonders on a meal, it's no surprise some may want to monopolize on it. However, usually the secret ingredient will be something simple, like a dash of herbs de provence, or a bit of lavender, rather than something exotic. Since the average consumer has an exaggerated impression of the secrecy, however, a company can deny revelations by spiteful former insiders or an attention seeker who just happens to get it right.
 * KFC's "eleven herbs and spices" (which, for the record, are ground oregano, chili powder, ground sage, basil, marjoram, pepper, salt, paprika, onion powder, garlic powder, and monosodium glutamate).
 * The "secret formula" for Coca-Cola is only secret so far as the exact proportions of the ingredients and the precise selection of certain minor trace flavors are concerned. Every grocery chain knows enough about what makes up the basic cola flavor (citrus oils, cinnamon, vanilla, nutmeg and phosphoric and/or citric acids) to create its own house brand, after all.  However, whether for intellectual property or marketing reasons, the Coca-Cola company enforces this trope on its regional bottling companies by selling them the ingredients as nine different unidentified "Merchandises" which are then mixed together according to special instructions provided by the company.  The first four Merchandises are known -- they are sugar (or high-fructose corn syrup, depending on the location), caramel coloring, caffeine and phosphoric acid, in order.  The exact identities of Merchandises 5 through 9 are still uncertain, especially the infamous "Merchandise 7X", which is believed to be a mix of essential oils specific to the flavor of Coca-Cola.
 * Cooking show chef Emeril always adds a dash of "essence". Bam! However, given how Emeril Lagasse has made the recipe for "essence" publicly available, this is less a Secret Ingredient and more a Trademark Ingredient.
 * Despite jokes made on comedy-oriented shows, the special sauce McDonald's uses has never been secret. Neither is it simply Thousand Island dressing, a common rumor. It is made of ketchup, sweet pickle relish, yellow mustard, onion and vinegar.
 * Another old (since 1930 in fact) rumor is that Dr. Pepper's secret ingredient is prune juice. Although the exact recipe is not public, this is not true.