Presently the questions in recipes seem to be mainly requests for recipes.
We can then write intuitive usage guidance accordingly.
Why would I think that this would be a useful tag? Several reasons.
So that I can find questions.
If this tag existed, I could probably pull out some of my mothers recipes. She cooks very good vegetarian food, as she used to be a vegetarian and my brother currently is, so we don't really eat meat a lot. As it is, though, I don't see any easy way to find questions like that.
To encourage more of these questions.
I'm pretty sure that these are on-topic. If you haven't decided, I can try to make a case for them (on a different meta post)*. But I don't really see any on the site right now.
recipes is unclear.
What's this tag supposed to be for? Requesting recipes? Asking about existing recipes, such as scaling for different people? Something else? The tag name does't give any hints, and the tag wiki (what tag wiki?) didn't help.
*All right. I'll make a small case for them right now.
It's something many veg*s will want.
Many veg*s face problems finding good recipes that are veg*n and still taste good, if my eavesdropping is anything to go by. A site targeted towards people who will often encounter a type of problem should, IMO, have that problem be on-topic.
It's something the userbase will know.
The users will know the veg*n recipes, simply by virtue of being veg*n. They can then help newer veg*ns by giving them some help with their recipes.
It's something that people will expect to be here.
I mean, it's one of the most common things for a veg*n to want, so users will expect to be able to ask about what they need. (I hope I made sense here; I'm not quite sure.)
Anyway, so if these are on-topic questions, you should have a way to categorize them.
As for having recipes be a synonym... I'm not sure. recipe-request will come up if you type
recipe into the tag box, so there's no concern about using the wrong tag. I would simply burninate recipes off of the face of the earth.