I have an ingredient that I'm not sure what to do with, can I ask how to use it? Can I ask for recipes including it?
A question asking how to use a specific ingredient is obviously about cooking, but it may not always be appropriate for a question and answer site.
In particular, when the ingredient in question is something commonly found and there are many possible uses involving it, then it will probably solicit a lot of answers, and questions which have lots of answers are not very useful (see this answer for why that is).
There are also an unlimited number of 'Uses of X' questions about common ingredients. We have to consider what would happen if we started to allow 'What are some uses for onions?' and 'What are some uses for chicken?'. Where would it end? These questions are recipe swap questions in disguise. And those are not allowed.
When the ingredient in question is rare or unusual then it will probably get fewer answers, which is generally preferable, and which will probably be more informative to people.
This implies that we will have to make a decision about which 'Uses for X' questions should be allowed and which should be considered Off Topic.
There are some guidelines both for asking and answering these sorts of questions.
When asking a question of this sort we should try and restrict the ingredients to:
Things which are extremely rare in most regions and thus not easy to find recipes for. This is obviously the most subjective, but we could consider things which are not available in a supermarket as the yardstick. This is not perfect, and any other suggestions are welcome. A question about sumac is an existing example of this. Please do your own homework and try the recipe search engines first.
When answering questions of this form we should consider:
Classes of uses are best. eg:
Used for flavouring cakes is preferable to a cake recipe
Flavour pairings in preference to a specific recipe
Your favourite recipe containing the ingredient is not generally going to be useful
So if you have a question of this form, go through this check list before asking it or it is likely to be closed.
Additional advice for people who have had a question closed and been referred to these guidelines:
If you are looking for information on how to use a common ingredient, please see the following question:
I would like to point out something which is not explicitely mentioned in this answer, but which has been the way we have used this policy over the past years.
Sam Holder's answer mentions that we don't cover ingredients which are so common that you can easily find recipes for them. We define this as being common somewhere in the world, as opposed to "in your country". So, examples like cornel cherries or whelks would fall under the "so common that they should be closed" policy even though I suspect most users of this site don't know that they exist, much less than they are edible.
This may strike you as unfair or defeating the point, but the alternatives are worse. First, we could define it as "so uncommon that the asker has never heard of them". This means that we have to accept questions on a lot of stuff which is a staple in our kitchens but not present somewhere else, bringing us back to square one with all the big list questions we are trying to avoid with this policy. We could alternatively define it as "uncommon in the US", which would cover the experience of the majority of our users, but that would be opposed to our policy of doing our best to be more international and make users from all countries feel welcome, so I'd rather not go there.
This leaves us with the policy of closing questions which many people here would consider interesting and would be sad to see go. I agree that this feels unpleasant on the first glance, but consider that we don't have to be everything for everybody. If a search of "X uses" or "X recipes" or "how to eat X" brings you enough search results, there is no need to rehash them on our own just because it is novel to us.