I've been meaning to try poaching a steak for a while now. Now hear me out before you tell me I'd be wasting a perfectly delicious piece of meat. I've poached fish a ton and by far the best thing about poaching is temperature control, the food you poach will never be warmer than whatever the temperature of the water is. Secondly poaching can infuse flavors deep into the food that are hard to get at otherwise. Thirdly poaching keeps foods that would otherwise quickly dry out nice and moist. So here's how I think about it in my head. While steak really benefits from a nice char on the outside it also is very important to have the inside cooked right. Maintaining a proper internal temperature is difficult as almost always you get a little slice of perfect in the middle, a ring of okay around that, a ring of well done, a ring of well this is rather dry, and then your char. So picture this: A light red wine, salt and pepper all mixed into a brine poaching a cheap steak (maybe a bad sirloin that always has a habit of turning to sawdust when cooked) that you've dry aged for a few days. The temperature is set to a perfect 135 and that steak now infused with all that salty, peppery, red winey goodness is now medium rare all the way through. Throw it into a skillet or onto the grill for 30 seconds a side to char and drain a little bit of the juices so it isn't water logged... in my head it tastes so good. Never had the occasion to try it but man, would I love to.
Unfortunately, I don't have time for a lengthy response. But I worked for a while at a high-end country club and we would occasionally Sous-Vide steak. This worked okay, but our idiot chef didn't sear them afterwards and they ended up flavorless. And I'm not sure about poaching, one of the absolute worst things you can do to beef is waterlog it, even surrounded by moisture, it will likely end up dry and tough. Such a small cut of meat won't do as well with a braise, and definitely won't function well in a poach. What you're describing is basically a single-serve braise on a small cut of meat. So you may be able to do it in a smaller amount of time if you sear it first, but otherwise you'll end up with a tough and dry cut of meat.
I'd agree that waterlogged steak is pretty much one of the worst abuses of beef you can manage. I was thinking that hopefully a few days of dry aging (not too long or else the enzymes will tenderize it too much) will stiffen up the steak a little so it doesn't absorb it all like a sponge. Additionally a smaller cut will mean less time in the water so hopefully less time to get all friendly with the moisture. Beef really benefits from dry heat and I certainly think it needs a sear before and possibly after. Even with all the potential difficulties I still believe it could be a very unique and delicious way to cook beef. Fingers crossed anyway.
Oh definitely give it a shot! I'd love to hear how it turns out. Like I said, I'm just wary about putting beef in water like that, but if you end up doing it, be sure to let me know what happens! You may want to try using beef stock with wine in it instead of brine, too.