Ottolenghi's One-Pot Baked Orzo with Mozzarella and Oregano

Ingredients

• 100ml olive oil
• 1 large aubergine, cut into 2cm dice (300g)
• 4 medium carrots, peeled and cut into 1.5cm dice (300g)
• 4 celery stalks, cut into 1.5cm dice (200g)
• 1 large onion, finely diced (170g)
• 3 garlic cloves, crushed 250g orzo pasta, rinsed
• 250g orzo pasta, rinsed
• 1 tsp tomato purée
• 380ml vegetable stock
• 3 tbsp fresh oregano, chopped, or 1½ tbsp thyme leaves
• grated zest of 1 lemon
• 120g hard mozzarella, cut into 1cm dice
• 40g Parmesan, grated
• 3 medium tomatoes, cut into 1cm-thick slices (400g)
• 1 tsp dried oregano
• salt and black pepper