In a large skillet, heat olive oil over medium-high heat. Add the sliced steak and cook for 3-4 minutes until browned. Remove from the skillet and set aside.
In the same skillet, add the sliced onion, bell pepper, and mushrooms (if using). Cook for 5-7 minutes until softened. Season with salt, pepper, and Worcestershire sauce. Remove from heat.
Roll Out the Dough:

On a floured surface, roll out the pizza dough into a large rectangle, about 10×14 inches.
Assemble the Stromboli:

Spread the cooked steak evenly down the center of the dough, leaving a 1-inch border on all sides. Add the cooked veggies on top of the steak. Sprinkle the shredded cheese evenly over the top.
Fold and Seal:

Fold the sides of the dough over the filling, then fold the top and bottom edges over to seal the stromboli. Carefully transfer the stromboli to the prepared baking sheet, seam-side down.
Brush with Egg Wash: Brush the top of the stromboli with the beaten egg for a golden, shiny finish. Sprinkle with sesame seeds if desired.

Bake:

Bake for 20-25 minutes, or until the stromboli is golden brown and the cheese is melted and bubbly.
Serve:

Allow the stromboli to cool for 5 minutes before slicing. Serve with marinara sauce or cheese sauce for dipping.
Helpful Tips:
Shortcuts: Use deli-sliced roast beef to speed up the process.
Extra Flavor: Add banana peppers or jalapeños for a kick of spice.