Heat a little olive oil in a large oven proof pot on a medium heat. Finely dice onion, carrots and celery and add to the pot as you chop. Add the star anise (if using). Cover and cook, stirring every few minutes until the veg are soft but not browned. Will take about 10 minutes total.
Add meat, using a spoon to break it up into smaller chunks. Add tomato passata / puree, balsamic, bay leaves (if using) and salt. Stir to combine then pop in the oven uncovered.
Cook for about 2 hours, stirring every 30 minutes or so. When the sauce has reduced and thickened, taste and season with more salt if needed and possibly a little more balsamic.
Remove and discard star anise and bay leaves (if using). Use immediately or store in glass containers in the fridge or freezer.