Trim: Slice each chuck roast in half along the fat seam. Remove any silverskin.
Brine: Heat the water in a large pot. Add the brine. Simmer until dissolved. Allow it to cool. Place the chuck roast in a meat prep bag. Fill with cooled brine. Close the bag, and place it in a large bowl. Refrigerate for 5-7 days.
Rinse: Remove the beef from the brine and rinse under cold water.
Season: Rub thoroughly with pastrami rub. Place on a baking rack on a sheet pan. Refrigerate uncovered overnight.
Smoke: Heat smoker to 250F degrees. Place the brined and seasoned beef on the smoker. Smoke for 2 hours. The beef will develop a mahogany bark.
Steam + Smoke: Place a disposable pan of water on the smoker. Continue smoking for about 30-90 minutes, until the internal temperature reaches 205-210F degrees. The smaller pieces will likely be ready in 30 minutes, while the larger ones may take 90.
Rest: Let rest 30 minutes. Slice and serve on toasted rye bread.
