DAY 1: Rinse and trim extra fat and loose ends off corned beef brisket flat. Put in a large container of cold water over night to extract extra salt. Change water out a few times if you want to remove more salt.
DAY 2: Fire up smoker to 250°. Liberally coat with Pastrami seasoning. Pat brisket dry and add a small binder of olive oil. Apply spices liberally over all sides of the brisket. Smoke 250° for 3 hr or 160 internal. Put in foil pan with no water and foil top for 2 hr or 200°+. Let rest on counter to cool down 1hr, drain Au jus into container, put in the fridge overnight.
DAY 3: Slice thin and steam 3 min on stove in a pot with strainer on top and water boiling on the bottom. Build sandwich to your liking and use Au jus for dipping.