Step 1

For the slow cooker pastrami spiced corned beef: Place the peppercorns, coriander, mustard seeds, sugar and 3 bay leaves in a spice grinder and pulse until very coarse, 8 to 10 pulses. Coat the entire corned beef in the yellow mustard, then coat the entire corned beef with the ground spices.

Step 2

Place the corned beef in a slow cooker along with the garlic and remaining 3 bay leaves; pour the stock over it until just submerged. Set for 8 hours on low or 4 hours on high and cook until super fork-tender.

Step 3

Remove, tent with foil and rest for 30 minutes. Slice into pencil-thick slices (about 1/4-inch-thick) and set aside.

Step 4

For the 18,000 island dressing: In a medium bowl, combine the mayonnaise, giardiniera, ketchup, sriracha, mustard and granulated garlic. Season to taste with salt and pepper and set aside.

Step 5

Assemble the sandwich: Heat a flat top griddle to medium heat. Spread the butter on one side of each slice of bread. Place four pieces of bread buttered-side down on top of the griddle. Top with a slice of cheese on half of the bread slices. Allow to cook for a couple of minutes. On the opposite side of the griddle, add two to three pieces of corned beef in two piles. Top with some sauerkraut, a spoonful of the dressing and cheese. Top with a metal bowl and add a splash of water to melt the cheese. Allow to cook until everything is melty and warmed through, about 2 minutes. Once the cheese has melted on the corned beef as well as the bread slices, top the bread with the corned beef and sandwich the bread together. Repeat with the remaining slices of bread and ingredients to make four sandwiches total.