Follow these simple steps to create your French Dip Tortilla Roll Ups:

1. Spread the Sauce: Lay a tortilla flat on a clean surface. Spread a thin layer of horseradish sauce across the tortilla. If using, spread a bit of Dijon mustard as well.

2. Layer the Beef: Place a generous portion of sliced roast beef on top of the sauce, covering the tortilla evenly.

3. Add Cheese: Sprinkle shredded Swiss cheese over the beef, making sure to spread it evenly.

4. Roll It Up: Carefully roll the tortilla tightly from one end to the other, ensuring all the fillings are wrapped inside.

5. Repeat: Repeat this process with the remaining tortillas until all ingredients are used up.

6. Slice the Rolls: Use a sharp knife to cut each rolled tortilla into bite-sized pieces, about 1-2 inches thick.

7. Heat a Skillet: In a large skillet over medium heat, lightly grease the pan. Place the roll-ups seam-side down in the skillet.

8. Toast the Rolls: Cook for about 1-2 minutes on each side or until the tortillas are golden brown and the cheese has melted.

9. Prepare the Broth: In a small saucepan, heat the beef broth over low heat until warm. This will be your dipping sauce.

10. Garnish and Serve: Transfer the toasted roll-ups to a platter, sprinkle with chopped parsley, and serve with the warm beef broth on the side for dipping.