I've looked at a few and I haven't loved any of them. They all have some kind of shortcoming that makes them not usable.

For example, the schema.org schema puts quantities, units, and ingredients in a single field. Fail, IMO.

Other issues include things like not being able to group ingredients or procedures.

I don't have my notes on what I thought of each of the ones I've reviewed handy, but here are some I've looked at:

- https://cooklang.org/

- http://www.formatdata.com/recipeml/

- https://recipemd.org/index.html

EDIT - for clarity, added examples of standards