Make the pesto. Place the basil, garlic, pine nuts and sea salt in a mortar and grind with a pestle to form a fairly smooth paste. Slowly add the oil until you reach the required texture (soft but not runny), then finally add the cheese and pepper, to taste.
Brush the aubergine and courgettes strips with the oil and season with salt and pepper. Cook on a hot barbecue for 2—3 minutes on each side until charred and tender.
Spread the rolls with some pesto, then fill with the grilled vegetables, tomatoes, mozzarella and rocket. Add a little extra pesto and serve hot.