Another winner! The steaks were nice and tender, and I was again reminded how inadequate the lighting is in my kitchen, because I broiled the steaks in the toaster oven and I really couldn't see how they were doing. I usually like my steaks medium, while darkwolfie prefers his well-done (actually, he likes them crunchy -- no, I don't understand it either). These ended up on the medium side of medium-well, and were as tender as if they were still bloody. (I had noted some nice marbling prior to putting them on the broiler; I'm sure that accounted for the tenderness.)
The butter was kind of messy to deal with; I wish I'd used a quart bag instead of a gallon bag when preparing it. Also, the balsamic vinegar separated out, and I had to pour that off. It took me a minute to figure out how to get the butter out of the bag, but I finally just cut away a corner and squished it out like frosting, into a bowl. It added just right amount of herbal flavor to the steaks -- I'm really looking forward to the second serving!
I didn't put it in as I took out the steaks, but we're also trying the peach crisp tonight, which is supposed to have a long baking period (1.5 hours at 350). Now that I think about it, though, I split that recipe, too, and it's in a much smaller pan, again in the toaster oven. I think I should check it at thirty minutes. I'll review it when it's done.
ETA -- Peach Crisp: darkwolfie took it away from me and put the other half of the pan in the fridge, lest I eat it all myself. It was that good. I knew it would be; when I preparing it, I was on more familiar ground. I don't have a feel for herbs and spices so much, but I'm a good baker, and I knew this was a winner as I put it together. Another gold star!