Late to the party but I cant resist helping a PNW neighbor.
Looks like you are using a
WSM, which is a great smoker!
Can you tell us a bit more about your procedure? What IT did you take the roast too?
For lamb, like other lean cuts it is really easy to over cook. I was taught that it is important to get lamb up to room temperature prior to cooking it. I am not so sure that is really needed but I still do that.
If your boneless leg is not netted or trussed, get out your butcher twine and tie it up. This will help keep the roast in shape, allow for even cooking and allow the juices to remain in the meat.
This cut is great for the rotisserie if you have one for your
WSM.
Mild woods work best in my opinion for lamb. Cherry, pecan, alder, apple, peach, kiawe or mixtures of these are all good.
I prefer to run the smoker hotter for a lean cut like this. I'll shoot for 325°. Because lamb is a mild meat you don't need much smoke so the higher temp works. If I was oven roasting the lamb I'd start at 450° for the first 15 or so minutes then drop down to 325°. But in the smoker it's straight 325°. Most important thing like any meat is to not overcook. If you had dry meat its because you overcooked the meat. We prefer medium rare and I pull the lamb at 125° and let the carry over during the rest take it up to the final temp. Which you need to rest the meat 30-45 minutes prior to slicing. I do this with loosely tented foil.
Rare: 120 to 125 degrees F – center is bright red, pinkish toward the exterior portion
Medium Rare: 130 to 135 degrees F – center is very pink, slightly brown toward the exterior portion
Medium: 140 to 145 degrees F – center is light pink, outer portion is brown
Medium Well: 150 to 155 degrees F – not pink
Well Done: 160 degrees F and above – meat is uniformly brown throughout
So that means that you need to have a good therm to test the IT (internal temperature). iGRill2, Maverick 732 or 733 are good multi-probe digital therms that allow you to monitor pitt and meat temps. The Lavatool Javelin is a great inexpensive instant read therm.
Along the lines of pit temp, don't trust the one in the lid of your
WSM. Mine are off by 20-30 degrees. Use a good remote therm to monitor pit temps.
Now with all that said there is no need for water in the pit to get moist meat. If you over cook it all the water in the world isn't going to help you. I run a dry smoke pit and the only time I get dry meat is when I inadvertently over cook it. Happens to the best of us.
