Why would a recipe specify Dijon mustard?

More on Dijon. The mustard is named after the city of Dijon, the capital of Burgandy. But it's not an AOC product. One would think that domestic labels would have to be called "dijonaisse" or something like that. But no. Grey Poupon is manufactured in the US (New Jersey, I think) and Maille is made in Canada. I'm perfectly content to buy the good stuff from the "cheese eating surrender monkeys" on the other side of the Atlantic.
Likewise there really is no such thing as California "champagne". Champagne is a specific region of France.

There actually is a chemistry side of dijon (or any mustard) when it comes to vinaigrettes -- mustard acts as an emulsifier and keeps the oil and acid from separating out. So in the case of a vinaigrette, you can use a different type of mustard than dijon, or you can use another type of emulsifier, which of course will greatly alter the taste: tomato paste, garlic, egg yolk, etc.

Thank you ChefOno-- very interesting! I wonder if squeeze bottles where less mustard is exposed to air are also under the 6 month rule, seems to have a longer expiration date.

One interesting article I read (cooks illustrated?) mentioned that mustard ages rather rapidly on the store shelf. Its flavor profile is best when its newer. It ages poorly. So when you buy. Look for a date lot that is newest. It loses its pugency before you even open it.

I have made this mustard from epicurious. After many dirty dishes and hours of prep, it did turn out wonderful--you could customize it. It was a very large batch, but it freezes well in an ice cube tray, so I have that homemade flavor whenever I want.

http://www.epicurious.com/recipes/food/views/Beer-and-Horseradish-Mustard-355236

Raye's. Made in Maine. Buy American.

http://www.rayesmustard.com/

Because dijon mustard is an amazing taste. And it's very hard to sub it.

I'm in the Maille camp. I think it exceeds Grey Poupon by miles. And I would also second the suggestion to try the grainier Maille variety, though the smooth stuff is my drug of choice.

very good question indeed! so will you be creating your own???

Mmm, try Ray's Mustard, stone ground way down east in Eastport, Maine. There are all sorts of varieties to try. Zingerman's sells a few of them, as does Whole Foods. Ray's has a web site.

Oh, and to the resident mustard maven – it may be worth trying whole grain dijon – it seems to me that its flavor profile is different than creamy dijon. Also, if you haven't tried Maille, it is the best easily accessible French-style mustard – puts the standard American dijon to shame.

Dijon is by definition a preparation of mustard with white wine, is my understanding. I don't much care for dijon on a sandwich, but it is the 'right' thing for salad dressing (the "pebbly kind", in my opinion). Gulden's spicy brown (hello sandwich!) is prepared exclusively with vinegar. Gulden's being spicy, and dijon not-so-much, maybe the wine mellows the heat? I think even the yellow stuff has it's place (I do not like cheetos, but yellow mustard on ballpark pretzels? Now we are talking my language of junk-food). My husband claims to have fallen in love with me because I had so many different types of mustard in my fridge. And I took that as high praise.

Dijon is mustard, French's is yellow "something".

Pierino is right on the money as usual. It's all about personal taste. I'm in neither the Dijon nor the French's camp myself. Guldens is a great alternative for both, center ground so to speak. Or Inglehoffer stone ground when you want some texture.

Yes, it is the taste. And digjon is on the spicier side but you can amp it up even higher if you want. But I wouldn't subsitute something like French's yellow mustard. There is a spectrum of flavor so you have to find the one that suits you, maybe one of those pebbly seed ones.