Pre heat the oven to 160C
Heat the oil in a large oven and hob proof casserole dish.
Fry the onion for 5 minutes, until soft.
Add the rest of the vegetables and the garlic and fry off for 7-8 minutes, stirring regularly.
Add the cumin, chilli powder and stir so all the veg are coated and fry off for a minutes.
Add the red wine vinegar and cook until this has been absorbed by the veg (couple of minutes should do the trick.).
Add the remaining ingredients, stir and bring to the boil.
Cover and place in the oven for at least an hour, the longer the better.
Once the sauce is thick and a deep rich colour, remove from the oven and add the sweetcorn.
Cover and leave to stand for 5 minutes.
Serve hot with whatever takes your fancy. We had ours with cheese nachos, which made for dunking.