Preheat your oven to 200°C/Fan 180°C/Gas 6. Trim the tops off the aubergines and cut them into bite-size chunks. Slice the tomatoes into 6-8 wedges each. Peel the red onion and slice it into thin wedges. Divide the veg between 2 large roasting tins.
Drain and rinse the chickpeas. Shake dry and divide them between the roasting tins. Pour 1 tbsp olive oil into each tin and season with a good pinch of salt and pepper. Toss the veg together, then slide both tins into the oven to roast for 25 mins. The veg will be tender and slightly caramelised.
Meanwhile, grate the lemon zest into a bowl and squeeze in the juice. Peel and grate in the garlic. Chop the mint leaves and add them to the bowl. Add the balsamic vinegar. Pour in 1 tbsp olive oil and add a little salt and pepper. Stir well.
Divide the roast salad between a couple of plates and drizzle over the dressing. Tear over the mozzarella and serve.