A few issues to consider: (1)
References are only 8% Helpful
It may feel like you are talking to the author one-on-one, helping them with your answer. But that is only a really, really small part of the picture. In reality, you are simply talking over their shoulder to a much larger audience. 92% of our traffic comes from search engines (I don't know if that is the exact number, let's just say its the "overwhelming majority"). If you provide a citation without any content, your answer does not help the other 92% of people find your information at all.
Ingredients Are Not Copyrightable
The text of the recipes is copyright by the author. But the mere list of ingredients is not. Copyright covers the "substantial expression" of directions, just not the information itself. So, you are free to copy the list of ingredients. You are also free to describe the procedure in your text, providing you don't use the author's wording.
Always Provide Attribution
Legal use or not, we focus on giving proper attribution to other people's works (see the cc-wiki license we live by). When using the work or research of someone else, it is strongly recommended that you provide a citation. It is more a matter of ethics and etiquette rather than Copyright law.
Fair Use Does Not Apply
I should say "...does not "necessarily" apply." Some believe that you can copy a recipe verbatim as "Fair Use" because it is only a small excerpt from the original text. That is not what Fair Use is about.
Fair Use not about quantity; it's about context. Fair use gives you the freedom to create original commentary on other people's works, not to appropriate the work of others. If you were to copy a passage of text from a cookbook to provide critique, you would likely be covered. If you were to copy that passage as part of a larger work of instruction, you would also be covered.
But cutting-and-pasting a block of text as an answer, in and of itself, is not covered by Fair Use. You can't claim to have created an original body of work if a substantial portion of the text is not your own.
(1) The standard "I am not a lawyer" yada-yada applies. Laws vary from country to country.