Combine au jus mix and 2 cups of water in a small saucepan over medium-high heat. Bring to a boil, then reduce heat and simmer for 5 minutes.

Lay the flour tortillas flat on a clean work surface.

Spread 1 tablespoon of horseradish cream sauce evenly over each tortilla, leaving a 1/2-inch border at the edges.

Place 2 slices of provolone cheese in the center of each tortilla.

Layer 2 ounces of roast beef over the cheese on each tortilla.

Distribute the caramelized onions evenly over the roast beef layers.

Roll each tortilla tightly, ensuring the filling remains compressed.

Optional: Wrap rolls in plastic wrap and refrigerate for 30 minutes to firm for cleaner slicing.

Slice each roll into 1-inch thick rounds using a serrated knife.

Serve the roll ups immediately with the warm au jus on the side for dipping.