Thinly slice the onion, garlic and celery. Finely chop the carrot and red pepper.
Heat half the olive oil in a large frying pan or casserole. Add the turkey mince and cook over medium heat, breaking it up with a wooden spoon, until it has changed colour and is lightly browned.
Drain off any excess liquid and transfer the turkey to a bowl.
Add the remaining oil to the pan. Add the onion, garlic, celery, carrot and red pepper and gently sauté for about 8 minutes, until the vegetables have softened.
Add the chilli flakes, Italian herbs and thyme. Stir for about 1 minute, then add the tomato purée and stir to coat the vegetables.
Add the chopped tomatoes and return the turkey mince to the pan. Pour in enough water to cover the mixture generously, then add the stock cube.
Bring to the boil, then reduce the heat and simmer for about 15 minutes, stirring occasionally.
Add the courgette and cabbage and cook for a further 10 minutes, or until the vegetables are tender and the sauce has thickened.
Taste and season with salt and freshly ground black pepper if needed.
Serve with your favourite pasta and scatter with the fresh herbs.