Preheat oven to 170C
Heat oil in a large saucepan and cook onion for a few minutes, until softened.
Add the minced beef and cook for 5 minutes until it has browned.
Stir in the rice portion of the rice risotto.
Add the flavour sachet, tin of tomatoes and 1 cup of water. Bring to the boil, reduce to a simmer and cook for 10 minutes.
Place this mixture into a baking dish and cover with overlapping tomato.
Sprinkle with cheese and bake for 20-25 minutes, until the cheese is golden.