Preheat a large griddle or 2 large non-stick saute pans on low heat. In a small saucepan heat the peanut oil until very hot. In a small bowl, whisk together the sugar and vinegar. Add the Szechwan peppercorns and pepper flakes to the hot oil and immediately add it to the vinegar. In a large bowl, mix together the cabbage, carrots and scallions. Toss the salad with the vinaigrette and season with salt and pepper. Lay out the slices of rye and top each 1 with a slice of cheese then a slice of seasoned turkey. Place a small mound of the slaw (use tongs to strain off excess liquid) on the turkey and close sandwich. Butter the top part of the sandwich. Add some butter to the griddle and move sandwich around to completely coat with butter. When brown, about 5 to 7 minutes, flip over sandwich and brown other side, 5 to 7 more minutes. Slice on the bias and serve hot.