baked orzo with eggplant and mozzarella

INGREDIENTS

• 1 large (mine was just over 1 1/4 pounds/570 grams) eggplant, cut into 3/4-inch dice
• Salt and black pepper
• 1/4 cup (60 ml) olive oil
• 1 medium carrot, peeled and cut into 1/4-inch dice
• 1 celery stalk, in a 1/4-inch dice
• 1 medium onion, finely diced
• 3 garlic cloves, minced
• 8 ounces (225 grams) orzo, a rice-shaped pasta, rinsed
• 1 teaspoon (6 grams) tomato paste
• 1 1/2 cups (355 ml) vegetable stock
• 1 to 3 tablespoons fresh oregano, chopped
• 1 teaspoon grated lemon zest or more to taste, up to the zest of a whole lemon
• 4 ounces (115 grams) mozzarella, firmer is better here, cut into 1/3-inch dice
• 1 1/2 ounces (a generous 1/2 cup or 45 grams) parmesan, grated
• 3 medium tomatoes, diced