Cooking recipes are often used to explain novice programmers about the concept of algorithms. There are some basic similarities to these two. So I ask myself, if there are open source programs, are there open source recipes? And if not, why not?
Many recipes are not actually copyrightable. Now a particular written form of a recipe may be, as would the formatting and accompanying photos of a recipe book, but a list of ingredients is not.
(I'm not sure when a recipe would become copyrightable. Maybe lists of ingredients never will be, but the steps to combine them are? This would be a good question for the Law SE site.)
Yes, there are open source cooking recipes. One example that is heavily in use is the microformat hrecipe. When used on websites, it not only declares the recipe in the markup, but makes it easily scrapeable for reuse.
A recipe I recently became aware of is open source cola. Just like the name suggests, it is the open source version (of one flavor) of soft drinks, and it stands out in contrast to its cousin, the king of proprietary closed recipes, coca-cola. You can read more on Wikipedia.