Heat the oil in a non-stick frying pan. Briefly fry the onion and garlic. Add the aubergine, season with salt, stir fry for approx. 5 mins. Add the meat and stir fry for a further 5 mins. Reduce the heat, add the tomato puree and cook briefly. Pour in the water, simmer the ragout for approx. 5 mins.
Bring the stock to the boil, stir in the polenta, simmer for approx. 2 mins. over a very low heat, stirring constantly to form a thick paste. Stir in the cheese. Serve the polenta with the ragout.