Sausage and Peppers on Bronx Buns

Ingredients
3 tablespoons olive oil
2 large yellow onions, sliced ¼-inch thick
Pinch red pepper flakes (optional)
Kosher salt and freshly ground black pepper
1 red bell pepper, cored and sliced ¼-inch thick
1 green bell pepper, cored and sliced ¼-inch thick
4 Italian sausages (sweet or hot)
4 Bronx Buns, split
3 tablespoons salted butter, melted
3 tablespoons sesame seeds
4 slices provolone cheese

Directions
Preheat oven to 400 degrees F. 

Heat 2 tablespoons of olive oil in a large skillet over medium-high heat. Add the sliced onions and season with a pinch of red pepper flakes, salt and pepper. Cook, stirring occasionally, until golden and soft. Stir in sliced bell peppers and continue to cook until browned in spots and softened. Remove from heat and set aside. 

Heat remaining 1 tablespoon olive oil in a separate large skillet over medium high heat. Add sausages and cook, turning often, until crips and brown on the exterior and cooked through. 

Brush the exterior of the pretzel rolls with melted butter and sprinkle with sesame seeds. Place on a baking sheet. Add a slice of provolone to each roll and top with a sausage, onions and peppers. Bake until the cheese is melted and the roll is lightly toasted, about 5 minutes. Serve immediately.