French Dip Sliders have all the best elements of the classic French dip sandwich—savory roast beef, melty provolone, and sweet caramelized onions—and transformed them into bite-sized sliders that are perfect for sharing!
To a large skillet set over medium heat, add the butter, onions, thyme, salt, and pepper. Cook, stirring once in a while till the onions caramelize. If the onions stick to the pan, add a teaspoon of water and keep cooking. Set aside.
Cut the buns in half, keeping them all together without pulling each roll apart. Lay one side in an oven safe casserole baking dish and top with the roast beef, followed by the cheese. Spoon the onions over the cheese and place the other half of the rolls over top, making a big sandwich.
To make the topping: In the same skillet you made the onions, add 3 tablespoons of butter, French onion soup mix, and Worcestershire sauce. Stir till butter is melted.
Spoon or brush the melted butter mixture over the top and exposed sides of the buns and sprinkle sesame seeds overtop. Bake uncovered for about 15 minutes, till the cheese is melty. Sprinkle with parsley after removing from the oven, if desired. Cut the sandwiches on the roll lines and serve hot. Dip in Au Jus, if desired.
Notes
Storage: Cover the leftover sliders with foil or plastic wrap or place in an airtight container and store in the refrigerator for 3 days.Freeze: You can also freeze them for up to a month—just wrap each slider in foil before freezing. When ready to eat, thaw and reheat in the oven.Reheat: To reheat, pop them in the oven at 300°F for about 10 minutes, or until warmed through. Alternatively, you can reheat in the microwave but the buns will end up quite soft.