With the rack in the middle position, preheat the oven to 425°F (220°C). Line a baking sheet with parchment paper.
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.
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.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.