When I have done it, I try to make sure there is beef broth in the the pan to keep it moist. I have done it with slices and usually try to get them wet in the broth before plating. I like to put the broth in a foil pan and put it on the smoker for an hour or so to give it some smoke flavor.
22.5" WSM, 18.5" WSM x 3
22.5" Weber Kettle x2, Smokey Joe
500 Gallon UBS
Super-fast Orange Thermapen
Proud Member of The West Coast Offense Team