Mistake

A Mistake is an item found in the Paper Mario series. The item is created when Mario mixes incompatible ingredients. A Mistake heals only one HP and one FP. Of course, the goal of cooking is not to make something like this. In Paper Mario: The Thousand-Year Door and Super Paper Mario, the Mistake counts towards finding all the recipes.

Interestingly, a Mistake is actually slightly more effective than a Dried Shroom, since it restores one HP and one FP, compared to the Dried Shroom, which only restores one HP. If the player cooks a Dried Shroom before returning Maitre Delish's Cookbook, he/she will get a Mistake. If, however, the player cook a Dried Shroom AFTER returning the Cookbook, he/she will get a Shroom Fry instead. Mistakes sell for three coins in Twilight Town, but one coin everywhere else.

In Super Paper Mario there are two types of Mistakes - and one of them is actually somewhat useful. By having Saffron cook a Sleepy Sheep, she will make another kind of Mistake that puts multiple enemies to sleep, similar to a Sleepy Sheep itself. In gact, upon using the item, the animation is the exact same as one; including the last sheep*.
 * This link brings you to the Sammer Guy of the same name.