Nicely done, BP! I was shopping last weekend but sadly the leftover rib roasts hadn't been marked down yet.
Did you leave the roast on the plank for the duration of the cook? I've never seen one done that way before.
Thanks! Yup, I've been using planks a little differently this year. I don't do this with cedar because it's too strong for me, but with oak and hickory planks I quit soaking them and I put them on the fire for a couple minutes to get them smoking (or maybe even burning) before shutting the lid. That puts the flames out but the plank continues to provide a lot of smoke for the duration. So it's more like smoke-roasting than typical planking. The good part is that I don't need to add any other smoking wood for flavor. The downside is that the planks are done after one use, and sometimes it's hard to get the food off because they flare up again when I open the lid. That wasn't a problem this time because I left it alone for an hour and a half and the plank was used up by then. In fact, the beef plank broke in half when I tried to remove it.
I've been told this won't work so well with grills other than a Weber Kettle, but I don't know why. I did it with a spatchcocked chicken a few months ago and it was my favorite of the year. It tasted like a smoked chicken even though it cooked in much less than an hour and had a nice crisp skin.