Sometimes it seems the most appropriate reply to a question is to provide a tutorial.
Is that appropriate or should one write the tutorial elsewhere? For example one could write the tutorial on a blog and provide a link to it. Is that the better option?
I'm skeptical personally. A unique and core value I see in sites like this one is summarization. I don't think it's necessary to import external content in bulk, and there's value in short, understandable summaries which point to the external content, whether it's created by the answerer him/herself or someone else, rather than the external content in full.
One of the aims of the site is to be the place for answers to all questions relating to photography and photographic editing. With that in mind, it would normally be better to outline the steps required in your answer, rather than linking to an external site.
As an aside, it's easier to spot a good answer that deserves being upvoted if it doesn't require a click through to an external site.
I don't see anything wrong with a tutorial-style answer, assuming that it answers the question at hand. If you were to link off the site, I think that you should, at minimum, provide a summarized version with the link. Like Rowland said though, if possible, putting it all on this site would be preferred, simply because it makes it easier for others to find the answer, and also, it avoids dead-link problems in the future.
To directly answer your question about "tutorial-style answers", I've done something similar, although not exactly like this, myself:
The general M.O. at StackExchange is to present a question that can be answered. I don't think there is any problem with a tutorial-style answer, so long as it is in response to a valid, viable, useful question. I would encourage you to pose your own questions and offer tutorial-style answers if you think they can be useful building blocks for our community.
Even if you don't need to ask a question yourself, there may be others who DO need to, or would like to and aren't able to figure out how to properly ask it. By both asking and answering questions yourself that you have a good answer to can help build up our community. Search engines will eventually pick up the content of your question and answer(s), allowing those who search for similar content to find the helpful content you provide.