This is somewhat related to 'Should “I need a recipe for X?” questions be off-topic?'. The idea is, if I really like dish/sauce/etc at restaurant Y - is a question asking - 'what is the recipe for [dish] at Y' appropriate? It does have a potentially correct answer although the chances of people knowing it (or willing to share it) are probably unlikely.
I'll take the opportunity of your question to re-assert the intention of my suggested moratorium on "recipe swap" questions. Hopefully people will link here for reference.
Are Recipe Requests Veiled, Indiscriminate Polls?
It was never my intention to suggest that recipes could never be discussed nor even mentioned on this site. However, I am trying to avoid the situation where the site fills up with lazy "I need a recipe for X" questions. But there is an important distinction between an indiscriminate recipe request (bad) and a recipe-related question (good).
Indiscriminate might be the distinction. "I need a recipe for X" is an indiscriminate question, asked without care nor making any distinction of why you are even bothering to ask experts. The answers aren't a product of expertise. It's barely a "real" question all. To me, it's akin to the shopping advice questions, banned on most sites.
Are restaurant mimicry questions allowed?
This question straddles right on the very edge of the on-topic side of the distinction I am trying to describe (above).
Someone can ask "What is the recipe for Red Lobster's biscuits?" (forget for a moment that no one knows the correct answer. irrelevant). But what they really should be asking is what makes them taste exactly that way. It's not an indiscriminate question when the criteria is so specific. The answer is very specific and, possibly, educational. As a recipe request, it's a poorly worded question. I would rather see it asked as "How do I get my biscuits to take more like Red Lobster's?" But that's a weird semantic argument that I hope people can see through. The important distinction is, are the answers going to be the work of someone's expertise in that area, or are the answers just the product of an indiscriminate shout-out poll?
The Caveat of a Moratorium
The danger of my suggested "moratorium on recipe requests" is that the mere mention or inclusions of a recipe in the post will trigger a knee-jerk reaction to shut down good questions. Recipes are the "language" of cooking and cannot be avoided. There's no recipes-are-a-dirty-word filter on this system. That's not my intention at all. To those people who are looking for that absolute true/false formula where you simply plug in a question and it comes out the other side happy... or it doesn't: Don't fall into that trap. Consider the context and the bigger picture.
These do have the potential to languish as unanswered questions and make the site seem stale, especially for local restaurants - even locally famous ones. The odds that more than one person on this site have even tried the perogies from Alycia's, let alone know how to replicate them is astonishingly small.
Large chain restaurants, on the other hand, will have far more people who've eaten there, and there will be a small chance that someone will know either the recipe, or a close match, but again, I don't think you'll have too many people rushing out to figure out the recipe for Boston Pizza's Spicy cactus dip, and we'll be left with more languishing questions.
On the other hand, it is a ready supply of interesting questions, which, if they can be reasonably answered, would supply a steady stream of google traffic.
I don't see how this is really any different than what's the recipe for X. I could a slightly more researched question being OK, though. Something along the lines of:
Restaurant X serves a ranch dressing that has a spicy (heat) kick to it. I'm trying to make it myself. I've made a ranch dressing following [recipe], and tried adding chili peppers A, B, and C to it to spice it up, but it wound up with an overly-pepper flavor. Any suggestions on how to spice up this dressing?
One benefit of asking the above question, is that it's not at all localized, even if that restaurant is in the middle of nowhere. The restaurant isn't even needed.
On Stackoverflow, users asking questions like, "What's the code to accomplish X?" are frowned upon because it appears they're just looking for an easy answer.
My opinion is that if you want a recipe, visit one of the hundreds or thousands of sites that publish, share, sell, or trade recipes!
This site should definitely incorporate recipes into the questions and answers, so someone asking "What's a recipe for a smooth X sauce?" might be accepted, because they are qualifying it a little. Kind of shorthand for saying "I have all these recipes for X, how do I identify one I'd like to use?"
I think as long as we use common sense and use a little judgment, we can accommodate recipe requests, but they have to show a little effort (just like on SO).
If the chain is big enough (and therefore not too localized), then I would think these are fair game because there is a right answer.