1 Slice the aubergine into thin strips lengthways and brush with harissa paste. Chargrill on each side until tender.
2 Place a bulb of garlic on a sheet of foil and drizzle with oil and seasoning and wrap up to enclose and place on a baking tray. Slice the tomatoes and place on the same baking tray and season with salt, pepper, and oregano and slowly roast the tomatoes for 20 minutes leaving the garlic in for a further 10 minutes.
3 Once the garlic has cooled slightly, sliced off the end and squeeze out the roasted garlic into a bowl with ricotta, sliced spring onion, and seasoning.
4 Lightly oil sourdough slices and grill until toasted.
5 Liberally cover toast with the garlic ricotta then layer rocket, grilled aubergine, and sliced mozzarella.
6 Melt the mozzarella under the grill or with a blow torch then close the sandwich with the final piece of bread and enjoy.