baked orzo with eggplant and mozzarella

Name: baked orzo with eggplant and mozzarella
Cuisine: European, Italian, Mediterranean
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