Heat the oil in your sauté pan over a high heat and add the mince.
Cook for 5-10 minutes until it is browned all over. Stir it occasionally with a wooden spoon as it cooks to break up the mince.
Add the garlic, onion, carrots and celery and cook for a further 5 minutes until the vegetables have started to soften.
Add the tomatoes, tomato puree, oregano and stock.
Reduce the heat to medium, put the lid on and cook for 15 minutes until the vegetables are softened and everything has thickened.
Add the orzo, stir well, put the lid back on and cook for 10-15 minutes, or until the orzo is cooked through, stirring occasionally. (If the mixture becomes too dry before the orzo is cooked, add a splash of water.)
Before serving, drizzle with the balsamic vinegar and sprinkle over the parmesan.
