Heat your oven to 200°C/Fan 180°C/Gas 6. Peel and grate 2 garlic cloves. Roughly chop the sundried tomatoes. Finely chop the rosemary leaves. Pour 1 tbsp oil into a baking dish lined with foil. Add the garlic, sundried tomatoes and rosemary. Pop it into the oven for 5 mins.
Pour the polenta into the baking dish, stirring it through the sizzling oil and aromatics. Season. Pour over 350ml boiling water and stir. Cover with foil. Slide into the oven to cook for 20 mins on the top shelf.
While the polenta bakes, peel and thickly slice the red onion. Trim and thickly slice the courgette into rounds. Halve the pepper and scoop out the seeds. Roughly chop it. Roughly chop the tomatoes. Trim the aubergine and chop it into bite-sized cubes.
Tumble all the prepped veg onto a baking tray. Drizzle over 1 tbsp olive oil. Season. Add the remaining 2 garlic cloves still in their skins. Slide into the oven on the shelf below the polenta to roast for 30 mins, tossing the veg halfway through.
After the polenta has cooked for 20 mins, carefully flip the baking dish over, so the polenta falls out on to a chopping board. Peel away the foil. Slice the polenta into thick chips.
Place the polenta chips back into the baking dish, spacing them apart. You may need another tray. This will ensure you have crispy chips. Roast the polenta chips for another 15 mins.
The veg should be cooked. Pluck the garlic cloves from the tray. Using the back of a knife, squeeze the flesh out from their papery skins. Mash it to a smooth paste and whisk it with 2 tbsp balsamic vinegar and 2 tsp smoked paprika. Pour this over the veg and gently toss to coat. Pop back into the oven for 5 mins.
Divide the chips between a couple of plates. Spoon over the roasted veg. Scatter over the oregano leaves and serve.