From the Super Mario Wiki
In Paper Mario: The Thousand-Year Door, the Omlette Meal is made by Zess T. at her house by mixing a Mushroom or a Life Shroom with a Mystic Egg. This meal restores five HP and five FP. It can also be obtained by spending the night at the Poshley Heights Hotel. It will be on the table the following morning.
Names in other languages