Turn your oven to 250C (480F) (don't worry the food won't be in there long enough to burn).
Spread the sausages and cabbage over a large rimmed baking tray so that everything is sitting in a single layer. I line mine with baking paper so it's easier to clean.
Pop in the oven. Set your timer for 10 minutes.
When the timer goes stir the cabbage and turn the sausages. If they need longer pop back in the oven for another few minutes.
When the sausages are cooked and the cabbage is tender drizzle over balsamic vinegar. Taste cabbage and season with salt and more vinegar if needed.
Divide sausages and cabbage between two plates. Scatter over your optional plus ingredient if using.