Heat the oil in a frying pan on the hob and add the onion and celery. Fry gently for 5 minutes, then add the courgettes, peppers, garlic, oregano, cumin and chilli powder. Fry gently for a further 5 minutes. Turn into a casserole dish and stir in the chickpeas.
Tip the canned tomatoes into the frying pan and add the treacle and vinegar. Bring to the boil and add to the casserole dish, stirring the ingredients to combine. Place on the lower rack of the halogen oven.
Set the temperature to 200°C (392°F) and cook for 50 minutes until thick and pulpy. Season with salt and pepper, and serve in bowls over a bed of steamed rice. Top with spoonfuls of soured cream, if liked, and scatter with chopped coriander to garnish.