In a large non-stick skillet over high heat, brown half of the beef at a time in 1 tbsp (15 ml) of the oil. As the meat is browning, break it up with a wooden spoon. Season with salt and pepper. Set aside on a plate.
In the same skillet, brown the onion and bell pepper in 1 tbsp (15 ml) of the oil. Return the meat to the skillet. Stir in the broth and Worcestershire sauce. Cook until the liquid has reduced by half. Adjust the seasoning.
Place the naan bread on the baking sheet. Divide the beef mixture among the naan and sprinkle with the mozzarella. Bake for 10 minutes or until the cheese is lightly golden brown.
Garnish
In a bowl, toss the lettuce and tomato with the remaining oil, the vinegar and oregano. Season with salt and pepper. Top the cheesesteaks with the salad and serve immediately.
