Perfect Homemade Pastrami Completely From Scratch

Pastrami:

1. Prepare the brisket by separating the point (the thicker, fattier, rounded end) from the flat (the thinner, leaner, rectangular end). Place the brisket on a large cutting board, fat cap facing down. Using a long thin knife, cut along the thick horizontal fat layer located between the point and the flat, lifting the flat as you cut through and stopping about mid-way through the meat. At this section cut the meat straight down in half. 
2. Trim excess fat from both cuts, leaving about ½-inch on the meat.
3. In a 12 qt container, combine the dark brown sugar, salt, coriander seeds, mustard seeds, cloves, curing salt,  red pepper flakes, bay leaves, rosemary, garlic, juniper berries and 1 gallon of cold water. Whisk until the salt and sugar have dissolved.
4. Gently lower the meat into the brine. If the meat is not fully submerged, fill a gallon-sized sealable bag with cold water and place on top of the meat. Cover the container and refrigerate for 6 days, flipping and rotating the meat on the third day.
5. Remove the brined brisket and set aside. Discard the brine, rinse the container well and fill it with 1 gallon of cold water.  Place the brisket into the water, cover and refrigerate overnight. 
6. Remove the brisket and pat dry with paper towels. Set aside on a large baking sheet.
7. Preheat the smoker to 225°F.
8. In a blender, coarsely grind the peppercorns, coriander and mustard seeds. Transfer to a medium bowl and add the light brown sugar, onion powder, garlic powder, and smoked paprika. Whisk until well combined.
9. Season the brisket generously with the spice blend, pressing it into the meat on all sides.
10. Place the seasoned brisket directly on the rack and smoke until the internal temperature registers 150°F, about 6 to 7 hours.
11. Preheat the oven to 325°F. 
12. Carefully transfer the hot brisket to a wire rack set over a large baking sheet. Pour 2-3 cups boiling water into the tray. Create a large tent made of foil and place it over the meat, crimping it along the edges of the pan, but leaving plenty of space for the heat to circulate between the top of the meat and the foil. 
13. Bake until the internal temperature registers between 195°F-203°F, about 2 hours.
14. Wrap each brisket in butcher paper and let them rest for at least 15 to 20 minutes.
15. When ready to serve, cut thick slices.

Russian Dressing:

1. In a medium bowl, whisk together the mayonnaise, ketchup, hot sauce, Worcestershire, smoked paprika, chives, horseradish, garlic and salt until thoroughly combined.

Reuben Sandwich Assembly:

1. In a saute pan, melt a generous amount of butter over medium-high heat. Place two slices of bread and toast until golden brown and crispy, about 1-2 minutes per side, adjusting the temperature as needed. 
2. Spread a generous amount of Russian dressing onto both pieces of toast. Place several thick slices of pastrami on top. If using cheese, drape it over the warm brisket. Spread an even thick layer of sauerkraut and top with the other slice of dressed toast.