Heat the olive oil in a skillet over medium heat and cook the onion and bell pepper, stirring occasionally, for 6 to 8 minutes, until soft and lightly browned.

Add the chopped roast beef, salt, and pepper, cook 2 more minutes just to warm through, then remove from heat and let cool completely.

Preheat the oven to 400°F and line a baking sheet with parchment paper.

Unroll the puff pastry on a floured surface into a 9x12 inch rectangle.

Scatter the cooled beef and vegetable mixture evenly over the pastry, leaving a 1/2 inch bare border on one long edge.

Sprinkle the shredded provolone over the filling.

Roll the pastry into a tight log starting from the edge opposite the bare border, ending seam-side down.

Wrap and chill for 15 minutes, until firm enough to slice cleanly.

Slice into 3/4 inch rounds with a serrated knife and place cut-side up on the lined baking sheet.

Brush the tops with beaten egg.

Bake for 16 to 20 minutes, until golden brown and the cheese is bubbling at the edges.

Cool on the pan for 5 minutes before transferring to a platter and serving warm.