Combine pepper & salt in a small bowl. Rub 2/3 of mixture evenly over surface of chuck. Reserve remaining 1/3 of mixture. Secure chuck roll with 2 to 3 pieces of twine tied around its circumference at 1- to 1 1/2-inch intervals.
Place chuck roll in a vacuum bag. (Fold over top of bag while you add beef so that no rub or juices get on edge of bag, which can weaken the seal.) Add 1/4 teaspoon liquid smoke to bag, if using. Seal bag using a vacuum sealer and let rest for 2 to 3 hours in the refrigerator.
Set your precision cooker to 155°F (68°C). Add chuck to water bath and cover it with a lid, aluminum foil, or table tennis balls. Cook for 36 hours. Allow cooked chuck to cool at least to room temperature, about 1 1/2 hours, before proceeding (an ice bath can speed up this process; cooling the meat will help the juices redistribute back into the meat so it is not as dry). Chuck can be stored in the refrigerator at this stage for up to 1 week before finishing.
Adjust oven rack to lower-middle position and preheat oven to 275°F (135°C). If your oven has a convection setting, turn it on and adjust heat to 250°F (121°C) instead. Remove chuck from sous vide bag and carefully blot dry with paper towels. (Liquid from bag can be added to your favorite barbecue sauce and simmered down to provide extra flavor.) Rub reserved salt and pepper mixture into surface of chuck. Place chuck on a wire rack set in a rimmed baking sheet and place in oven. Roast until a deep, dark bark has formed, about 2 hours. Continue with step 8.
Remove from heat, transfer to a cutting board, tent with foil, let rest for 15 minutes before serving.
To serve, slice meat in half with its grain, running knife in between the two largest muscle groups to separate them. Discard twine and place the two halves cut side down on cutting board.
Slice meat thinly against the grain, using a sharp chef’s knife or slicing knife. Serve beef with sliced onion, pickles, and white bread. For best results, slice only what you are serving. Remaining chuck can be wrapped in foil and stored in the refrigerator for up to 1 week. Reheat leftover chuck in a 275°F (135°C) oven directly in the foil until hot, about 1 hour.
