Preheat the oven to 160°C.
Prepare vegetables by cutting lids off peppers and tomatoes, and hollowing out aubergines and courgettes.
Finely chop the reserved vegetable flesh from the tomatoes, aubergines, and courgettes.
Heat 45ml of olive oil in a pan and fry the onion and garlic for 5 minutes.
Add the chopped vegetable flesh and tomato purée, cooking for 10 minutes until soft.
Stir in the rice and 150ml of vegetable stock, then simmer for 10 minutes.
Season with salt, pepper, herbs, and chilli flakes.
Arrange vegetable shells in a roasting tin, fill with the rice mixture, and replace lids.
Drizzle with 45ml of olive oil and pour the remaining 100ml of stock into the tin.
Cover with foil and bake for 1 hour.
Remove the foil and bake for another 15 to 30 minutes until cooked through.