In a large stockpot add the 3 quarts of water, kosher salt, pink curing salt,
white sugar, brown sugar, honey, pickling spice, coriander seeds, mustard seeds, minced garlic and oregano. Stir well and place over medium-high heat and cook until it begins to boil.
Remove from the heat and let cool. Stir then add the 3 quarts of ice water.
Pour the cooled brine mixture into a large container. Add the trimmed brisket and make sure it is submerged. Cover with a lid and place in the refrigerator for 5 days. Be sure to flip the brisket daily.
Remove the brisket from brine and lightly rinse with water. Thoroughly pat the brisket dry with paper towels.
In a small bowl, combine the coriander, black pepper, paprika brown sugar, and dry mustard. Rub the brisket generously well with the rub on all sides.
Leave the brisket out on the counter to warm up closer to room temperature, about 1 to 1 ½ hours.
Preheat the smoker to 225 degrees F. Add some apple wood chunks and cherry smoking chips. Place the brisket in the smoker and cook for about 4 to 5 hours or until the internal temperature is 160 to 170 degrees F.
Remove the brisket from the smoker. Add more wood and open the vent halfway to let the smoker heat to about 300 degrees F.
Wrap the brisket well in aluminium foil and place it back in the smoker and cook for about 1 to 2 hours until the internal temperature is 200 degrees F.
Remove the brisket from the smoker and let it rest for about 30 to 45 minutes. Thinly slice against the grain. To assemble the reuben sandwich: spread some of the Thousand Island sauce on the Rye bread. Top with pastrami, sauerkraut, cheese and more dressing.