Preheat the oven to 180°C (350℉).
Score the top of tomatoes (stem side) with a large "X" and arrange in a baking dish, scored-side facing upwards.
Quarter the red pepper and remove the seeds and white inner membrane.
Peel the shallots and cut in half vertically.
Place the cut red pepper, shallots and star anise pods in between the tomatoes.
Drizzle over a generous glug of olive oil and balsamic vinegar.
Season with salt, freshly ground black pepper and sprinkle over light brown sugar.
Roast in the middle rack of the oven for 45-55 minutes until tomatoes are soft and caramelised.
Remove from oven and pour over stock (enough to cover tomatoes). Return to oven for a further 15 minutes.
Remove from oven and set aside to cool slightly.
Once cool enough to handle, peel off the skins of the tomatoes and red peppers (optional - lends to a smoother texture). Remove the star anise pods.
Scoop out the roasted vegetables and add to a food processor or blender. Pour in the liquid from the roasting pan, scraping any caramelised residue with it. Pour over remaining stock (if any). Add the fresh basil and blend until smooth. Season to taste.
Serve with a drizzle of olive oil or a swirl of mascarpone cream.