They are most likely using lemongrass and fish sauce. I make a halibut dish that I flogged out of a local Vietnamese chef that involves marinating halibut in lemongrass, fish sauce, olive oil and chili paste. But we digress here.
Yes, experimentation is in order, preferably by way of moules provencale with a side of pommes frites and a crisp chardonnay.
Oh man…ohmanohmanohman…Brussels in mussels season…
Wild mussels are not as tastey as the mussels that are farmed. The farmed mussels are fed a diet that makes them just right.
Also, mussels are one of a variety of sea creatures particulary sensitive to contamination.
"What if a Wholey Mussel does not open?
Sometimes a mussel does not open and can be opened with your fingers or a knife. They still should be good to eat. A foul odor usually indicates if a mussel has gone bad…"
So then I would be remiss if I digressed thusly?
http://fooddownunder.com/cgi-bin/search.cgi?q=mussel
And with that, I think I’d better stop torturing you folks and get some lunch…and why, oh why is Chicago not located on an ocean, darnit?
I dunno about that. The last mussels I had were scooped off the floor of the Labrador Sea near St. Anthony, Newfoundland. We just used a medium mesh net attached to about an eight foot long pole. Scooped up a big ole tub of 'em in about 3 minutes. Boiled 'em less than an half-hour later in a coffee can on the beach (well the rocks that passed for a beach) over a driftwood fire one of the many little islands out there. Best ones I ever had. Ya gotta boil ‘em in their native sea water tho’ - or so the native Newfoundlander told me. Just the mussels and the salt water, no butter, sauces, herbs or nuttin. Mmmm-mmm-mm.
This is my experience - the shell gradually opens and then stops when the edges of the shell halves form 30 to 45 degree angle. Just the right amount to prise the delectable little gems from their haven.
No, you can purchase frozen mussels which are already dead. The shells still open most of the time, but not always. That indicates to me that it isn’t a factor.
It did to me, too, so I dug out my 1967 Joy of Cooking. It says that mussels are done steaming when they open, but doesn’t say a word about discarding closed ones. So it is possible that '75 is correct.
Wild mussels are gathered from the bottom of the sea, where they have to watch out for crabs, starfish and other predators. In their defense they grow a tougher, thicker shell.
Farmed mussels are grown on vines suspended above the ocean bottom. These mussels do not have to worry about predators, so they spend more time and energy growing body mass instead of growing shell. The result is mussel with a lighter shell and a plumper, more tender meat. They are therefore a better food value with a higher meat to shell ratio than the wild variety.
Back to the OP. Openeing a closed mussel is okay. I’ve seen several sites about it and provided a link to a mussel grower. It’s actually on the ** front end** that you want to concern yourself: Don’t cook a mussel that isn’t closed, because it could have been dead for some time.
Now that I hung up with my chef friend, he wanted my to talk about why closed but cooked mussels are often discarded: Because they didn’t open, the mussel might be overcooked causing the meat to be less than desirable. This would lead to people interpretting the mussel as ‘bad’.
So, open the closed ones after cooking and enjoy (if the meat hasn’t been ruined by the pressure/temp) and don’t cook the mussels that are opened.
I agree, however it was my thought that perhaps a mussel that fails to open is long dead, as opposed to fresh (or fresh-frozen) - this would make sense if the muscles and other structures had started to decay a little.
All I’ve got to say is:
Tomato garlic sauce, over homemade pasta.
That is, uh, closed ones, uh, maybe won’t get good sauce on them, so you want to discard them. Maybe that’s it! Yeah, there’s a possibly answer.
(Darn supermarket out of mussels just before I got there two days ago…)
Still clinging to our tired little theory, are we? Wellllllallllrighhhhhtythen…
TO THE LABORATORY!!
::burp:: S’okay, they all opened…nothin’ to see here…
Yes, to the laboratory! With chopped garlic and parsley in molar quantities.
Not to nudge this thread ever closer to being moved, but dare we discuss the proper eating method for mussels? But of course we do.
The only acceptable method is the Belgian method. One picks up the first mussel, removes the meat with a fork and eats it; put the fork down and do not touch it again upon pain of ostracism; use the empty shell as a pair of tongs to retrieve another mussel; grasp the uneaten mussel by its shell; pick the meat out with the shell tongs; consume; repeat.
Ah, now you see there’s something significant about what you just said.
The empty shell naturally springs open; I propose that this is also the case while the organism is alive (or freshly dead) - that the hinge ligament is sprung in such a way as to tend to open the shell and that the organism inside exerts constant muscular force against this spring action, to maintain closure of the shell.
however, upon cooking, the muscle attachment to the shell (which I’m presuming is some kind of gelatinous tendon or sheath-type arrangment) dissolves and the shell opens.
Sound plausible? Does to me.
I thought it was about time we did some actual research on the subject and found this:
So, am I’m right in saying that cooking mussels typically causes the meat to become detached from the shell? If so, then the shell opens naturally.
So, reasons for the shell NOT opening would seem to be:
-something wrong with the ligament (maybe decayed and lost its elasticity in a mussel that has been dead too long to be safely eaten)
-Failure of the meat to detach from the shell, perhaps ‘just because’ or perhaps a large amount of sand inside could act as a heat sink and prevent the thing from cooking fully…
Or another reason might be that the ‘lips’ of the shell adhered to one another during cooking - the rim of the shell is the newest part and it is sometimes softish - it’s easy to imagine this getting gummed together under heat.
On behalf of the now-liberated Southeast Asians, I cry European cultural colonialism! There are no inferior mussel-eating methods, only different ones!
Hmmm…it pains me to say you may have something here. But it doesn’t address whether or not it’s safe to eat unopened mussels or not. You may have solv-ed the mysterie, Clouseau.
::mangez-toi zis, damn you!::
I suspect that any of the reasons could apply to different unopened mussels in the same batch - some of them may be simply gummed up at the shell edges, others may have failed to detach from the shell and yet others might have decayed a bit, in which case some would be safe and others less so.
“UncleBeer
Straight Dope Science Advisory Board”
Ooh, look at Mr. Special Custom Title! 
Spiffy. That “Member” never did look right.
I hate these damned food threads.
I sticking with Lydia (the Italian-American chef, whom I shall marry) on this one.
All the yummy little rascals should be closed when you start to cook 'em. You might have to pester them some to get the open ones to close. If they don’t, toss 'em.
Cook them in a really good, extra garlicy, marinara sauce, which is for the bread. The mussels themselves are delicate and don’t need dressing, imo. The essence of the sauce that gets on during cooking is plenty.
I tiss the ones that don’t open, but most of them usually do.
I also like mussels in putanesca sauce, on spaghetti. Yes, I use the shells as tweezers.
I’m crying.
Peace,
mangeorge
BTW; I don’t know of any food from the sea that should smell bad.