Preheat the oven to 350 F.
Grease an 8 x 11 or 9 x 13 baking dish on the sides and bottom of the pan with butter.
Cut each of the rolls in half to separate the tops and bottoms. Layer the bottom half of the rolls into the baking dish.
Next, layer six slices of provolone cheese on the rolls. Add all of the roast beef on top of the cheese. Add a layer of French fried onions. Then top with the remaining six slices of cheese and the top of the Hawaiian rolls.
In a microwave-safe small bowl, mix together butter, 1 TB of the au jus seasoning mix, Worcestershire sauce, the onion powder, and half of the sesame seeds.
Microwave until the butter melts and then whisk until blended.
Brush the melted butter mixture on the top of the rolls with a pastry brush until well coated. Sprinkle the remaining sesame seeds on the rolls.
Bake in the oven for 18-20 minutes or until cheese is melted and rolls are golden brown on top.
While the sliders are in the oven, it is time to make the dipping sauce.
In a small saucepan, mix the remaining au jus seasoning with 1 ½ to 2 cups of water. Bring it to a boil over medium heat, then reduce to a simmer. Cook for approximately 5 minutes or until sauce is thickened, stirring occasionally.
Once the sliders are out of the oven, cut into individual sandwiches and serve with a cup of dipping sauce.