A Recipe is many things - but primarily you can see it as as template document containing instructions that will ensure the task gets done really well. These instructions usually are a mix of things like

1. pre-requisites - things that must be specified before you start (like the color you should use for something)
2. steps needed to perform an activity (like 1. let customer fill in form X; 2. verify Y; 3. Implement step a, b, c; 4. Inform customer; ...)
3. links to sub-recipes for very detailed instructions or shared process parts
4. images (often screenshots) to explain certain steps
5. LEAN tooling
   1. shortcuts to get the work done quickly - like links to websites / tools
   2. links to document templates which you should use
   3. links to additional information / documentation to understand what you're doing
   4. templates / snippets of text for use in communication, coding etc.