In a large skillet over medium heat, add the ground beef. If you're using dried minced onion, sprinkle it in now. Cook the beef until it’s browned, breaking it apart with a spoon as it cooks. This should take about 5-7 minutes.
Once the beef is nicely browned, stir in the can of tomato soup and the can of enchilada sauce. Mix everything together until well combined and let it simmer for a couple of minutes to meld the flavors.
While the beef mixture is simmering, preheat your oven to 350°F (175°C). Next, take each flour tortilla and spoon a generous amount of the beef mixture onto the center. Sprinkle a little cheese on top, then roll the tortilla tightly around the filling.
Place the rolled enchiladas seam-side down in a greased casserole dish. Once all the enchiladas are in the dish, pour any remaining beef mixture over the top. Finally, sprinkle the remaining cheese evenly over the top of the enchiladas.
Cover the casserole dish with aluminum foil and bake for about 20 minutes. After that, remove the foil and bake for an additional 10-15 minutes, or until the cheese is bubbly and golden brown.