1. Preheat oven at 180°c.
2. Spread 4 buns on a baking tray and put some marinara sauce on each.
3. Add chopped veggies namely onion, green capsicum, red and yellow bell pepper evenly on each bun.
4. Sprinkle oregano, chilli flakes, salt and black pepper to taste.
5. Now add some cheese.
6. Bake in the oven for 10-12 minutes, until cheese melts completely.
7. Take out from the oven and serve hot.