In a large skillet, heat olive oil and butter over medium-high heat. Add diced onions and red bell peppers. Cook, stirring regularly, until softened and slightly caramelized.

Spread parchment paper on a work surface and roll out the puff pastry sheet slightly. Cut it into three equal sections.

Spoon equal amounts of the onion and pepper mixture down the center of each section, then add a line of warmed BBQ pork over each.

Fold the edges of each puff pastry section over the filling, securing the edges together. Flip each roll seam-side down.

Brush the top of each roll with the whisked egg and sprinkle with everything bagel seasoning.

Cut each roll into 2-inch pieces and place them on a baking sheet lined with parchment paper.

Bake in the oven at the temperature indicated on the puff pastry box, until golden brown.