1. Preheat your oven to 400°F (200°C) to start preparing the potatoes.

2. Pierce the baking potato several times with a fork to allow steam to escape during baking.

3. Place the potato in the oven and bake for about 45 minutes, or until it's tender when pierced with a fork.

4. While the potato is baking, prepare the beef rolls by mixing the fresh cheese, parsley, Dijon mustard, salt, and pepper in a small bowl.

5. Lay the beef slices flat on a surface and spread a tablespoon of the cheese mixture onto the center of each slice.

6. Roll up the beef tightly and secure with toothpicks if necessary to keep the filling in place.

7. Heat the oil in a large skillet over medium heat and add the beef rolls.

8. Cook the beef rolls for about 5 minutes on each side, or until they're cooked to your desired level of doneness.

9. Remove the beef rolls from heat and let them rest for a few minutes before serving.

10. Serve the beef rolls with the crispy baked potatoes and a side of creamy mustard sauce.