In a mini chopper or food processor, puree the pepper, garlic, mustard and vinegar.
Pour the puree into a small nonreactive saucepan. Add the sugar and bring it to a boil. Lower the heat and simmer the mixture for 5 minutes.
In a small bowl, mix the flour with 1/2 tablespoon water to make a smooth paste. Whisk it into the pepper mixture and continue to simmer for 5 minutes, stirring regularly. Let the sauce cool.
Combine the cabbage, garlic, onion, jalapeno, vinegar, mustard, mayo, sugar, salt, Worcestershire sauce, and ShaSha sauce in a large bowl. Cover in plastic wrap and refrigerate for one hour.
Preheat grill to high heat (about 450° F, 230°C).
In a large bowl, combine the ground meats with salt and pepper. Form patties.
Grill the burgers for 3-5 minutes per side, or until your desired doneness.
Meanwhile, place a few slices of pastrami in 4 piles over indirect heat on the grill. Top with Swiss cheese. The lid of the grill needs to be shut to melt the cheese.
Place the buns, open face down on the warming rack or side of the grill (not over direct heat), until warmed.
Arrange buns on platters. Top with the slaw, a patty, and a mound of pastrami and cheese. Cover each with remaining bun tops.