Preheat oven to 400 degrees F. Line a baking sheet with parchment paper.

On a cutting board, slice the green pepper thin. Cut the onion into rings. Then, cut them in half to make long slices.

Heat a cast-iron skillet on medium-high heat and add the oil.

Place the ribeye steak in the pan and brown it well without moving it for about 5 minutes.

Flip the steak over and cook about 5 more minutes.

Remove the steak from the pan and add the veggies to the pan. Cook and stir for 5 minutes and remove from heat.

At the same time, cut the Ribeye into thin slices.

Place each piece of puff pastry onto the baking sheet next to each other.

Layer the provolone cheese slices down the center of each dough.

Layer the steak, bell pepper, and caramelized onions over the cheese.

In a small bowl, whisk together the egg and milk.

Fold in one side panel of each pastry. Brush the panel with the egg mixture and fold the second side panel over the first. Press a little to help seal.

Flip both pastries over so the seam sides are down.

Brush the top and sides of the pastry bundles with more egg mixture.

Cut three slits in the dough tops to allow steam to escape while baking.

Bake for 25 minutes, until puffed and golden.

Let stand for 10 minutes before slicing and serving.