Preheat oven to 160 C fan.
Place onion, courgettes, garlic, oregano, tomato paste, oil, 1 1/2 teaspoons salt and good grind of pepper into a large ovenproof cast iron saucepan that has a lid. Put on the lid and place in the oven for 55 minutes. Give the vegetables a stir half way through. You want all the veg to have cooked down but the courgettes to still hold their shape. Remove from oven and increase heat to 180 C fan.
Stir the tomatoes gently into the saucepan and then return it to the oven without the lid. Cook for 25 minutes until the tomatoes have burst and the vegetables have taken on some colour. Remove from oven.
Pick out the oregano sprigs and then leave the vegetables to cool for half an hour. They are best eaten warm or at room temperature.
While the courgettes are cooking you can get on with making the pangrattato Put the oil in a medium sized pan over o medium-high heat and then add the panko, pine nuts, garlic, 1/2 teaspoon salt and a good grind of pepper. Reduce the heat to medium. Cook for 6-7 minutes, stirring repeatedly until the mixture is a nice brown colour and is crispy. Place in a bowl for serving
When you are ready to eat, stir the lemon juice and basil into the courgette mixture and dish it up in a serving dish that has a lip as there will be a lot of sauce. Sprinkle over a generous handful of pangrattato and pass around the rest in its bowl.