Only use when asking for learning methods or resources. Don't use it when you are asking something specific and want to learn the answer.
This tag should be used only when you have a question about the process of learning to be a better cook. Examples:
Do not use the tag when you have a specific thing you want to learn and are asking how it is done.
Examples which should not have the learning tag:
Even though the OP there does not know how to make tomato paste or roux and wants to learn it, this tag should not be used. All our questions are asked because the asker wants to learn some new information or a new skill. If we were to use the tag on all of them, it would be useless.