In a large mixing bowl, combine the ground meats, chopped yellow onion, chopped garlic, green onions, egg, bread crumbs, Worcestershire, 1 teaspoon of the salt, and 1/2 teaspoon of the cayenne. Mix well with your hands and form into 16 meatballs. Insert a garlic clove in the center of each meatball and pinch the meat around it. Combine the flour and Creole seasoning in a shallow plate. Roll the meatballs evenly in the flour mixture, tapping off any excess. Reserve any remaining flour. In a large skillet, heat the oil over medium heat. Add the meatballs and brown evenly, using a spoon to turn them. Remove the meatballs from the pan and set aside. With a wooden spoon, scrape the bottom of the pan to loosen any brown bits. Stir in the reserved seasoned flour. Stir constantly for 3 to 4 minutes to make a dark brown roux. Add the sliced onions and season with the remaining 1/2 teaspoon salt and 1/4 teaspoon cayenne. Cook, stirring constantly, until the onions are slightly soft, about 2 minutes. Slowly pour in the beer and water and mix well. Bring to a boil and return the meatballs to the skillet. Reduce the heat to medium-low and simmer, uncovered, for about 1 hour, until the gravy is thick, turning and basting the meatballs with the pan gravy about every 15 minutes. Remove from the heat and skim off any fat that has risen to the surface. Add the parsley. Cut the loaf of bread lengthwise in half. Spread one half with the mustard and the other half with the mayonnaise. Arrange the provolone on the bottom half of the bread, overlapping the slices, then arrange the meatballs on top of the cheese. Spoon the gravy over the meatballs. Top with the remaining bread half, cut into 6 equal portions, and serve immediately.
Combine all ingredients thoroughly.