Heat your oven to 200°C/Fan 180°C/Gas 6. Set a roasting tray on the top shelf to heat up.
Tumble everything onto your preheated roasting tray. Add 1 tbsp oil. Season well. Shake so there’s just a single layer. Roast for 20 mins or till the veg is tender.
Halve the aubergine lengthwise and cut into 1 cm-thick slices. Halve, peel and cut the onion into 2cm slices. Slice the pepper into 2cm-thick slices (discard the stem and seeds)
Tip the tomatoes into the roasted veg with 1 peeled and chopped garlic clove. Fill the tomato tin with hot water and add to the veg. Return to the oven for 5 mins. Blitz in a food processor/blender. Add more water if needed.
Peel and finely chop the other garlic clove and the oregano leaves. Mix with the zest from your lemon, 3 tbsp lemon juice and 3 tbsp oil. Blitz in a food processor. Season to taste. Add more oil, if needed.
Serve the soup with a drizzle of the oregano pesto.