Preheat the oven to 180C.
Line a baking tray with baking paper. Place the zucchini, eggplant if using, capsicum and tomatoes on the lined tray. Season with pepper, spray twice with oil and bake for 10 minutes. Remove, toss gently and continue to cook for a further 10 to 15 minutes, or until tender.
Meanwhile, heat a non-stick frying pan over medium-high heat. Spray pork once with oil and season. Cook for 6 minutes on one side. Turn over and cook for another 2 minutes, or until cooked through. Remove and allow to rest for 2 minutes.
Transfer roast ratatouille to a serving plate and top with pork.