Finely chop the onion and sweat it. Add the minced meat and roast until the liquid is gone. Salt and pepper. Add the rice and mix with the meat.
Then stir in the tomatoes. Gradually add water or broth and cover and simmer gently on a low heat. Stir again and again as it burns easily. If the rice is still too hard, add a little more.
When the rice is cooked and the liquid is cooked, add the chopped parsley. Season if necessary, stir in the parmesan and serve.