Prepare a medium-hot fire in a charcoal grill with a cover or preheat a gas grill to medium-high.
To make the sauce, combine mayonnaise, horseradish, Worcestershire sauce, mixing whole grain, pepper sauce and red pepper flakes in a bowl mixing well; cover and refrigerate.
To make the slaw, combine the Napa cabbage, purple cabbage, red onion, fennel and yellow pepper in a bowl and chill. Prepare the slaw dressing by combining the sugar cane vinegar, whole grain mustard and slowly incorporate the extra-virgin olive oil while whisking. Refrigerate the dressing. 15 minutes before serving pour the dressing over the slaw mixture and toss. Add the crumbled blue cheese and toss again evening combining the cheese. Add salt and pepper. Drain off excess liquid and chill the slaw.
To make the glaze, combine root beer soda, chili sauce, lemon juice, Worcestershire sauce, dark brown sugar, molasses, liquid smoke, root beer extract, ginger, garlic powder and onion powder in a heavy medium saucepan. Bring to boil over medium heat, stirring occasionally. Reduce the heat to medium-low and simmer until reduced to approximately 1 cup, about 20 minutes. Glaze should be thick enough to coat the back of a spoon. Season the glaze to taste with salt and pepper. Set the glaze aside (it will thicken slightly as it cools).
For burgers place ground chuck in a large bowl in a cold refrigerator for 1 hour prior. Add in pepper sauce, green onions, salt and pepper. Handling the meat as little as possible to avoid compacting it, mix well. Quickly shape beef mixture into 6 round, equally sized patties. Cover with plastic wrap and set aside until ready to grill.
Brush grill rack with oil and place patties on grill, cover and cook, turning once, until done to preference, 5 to 7 minutes on each side for medium. Just before patties are done brush with root beer glaze.
Meanwhile, brush melted butter on top and bottom buns. Position buns; cut size down, on the outer edges of the grill for the last 2 minutes of grilling to toast lightly.
When patties are cooked, remove from grill, and keep warm while resting.
To assemble burgers, spread a generous amount of the Zydeco sauce over the cut sides of the buns. On each bun bottom, add a burger patty and brush again with root beer glaze. Add a portion of blue cheese Mardi gras slaw. Add the bun tops and serve.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.