1. Heat a large casserole dish over medium heat and add the oil and onion. Fry the onion for about 10 minutes until softened and fragrant and just starting to brown. Add the cumin,paprika,oregano and cinnamon and stir well. Add the mince and mix with the spices and fry for a few minutes until lightly browned. Add the three bean mix,passata,chipotle (if using),around ½ cup of water,the sugar,salt and soy sauce and mix well. Bring to a simmer,cover and simmer for about 90 minutes,stirring occasionally. Season to taste.
2. While the filling is cooking,bring 4 cups (1 litre) of water to the boil and whisk in the instant polenta. Whisk over medium heat until the polenta is cooked,about 6 minutes,then stir through the corn kernels and 1 cup of the grated cheese.
3. Heat your oven to 180C fan-forced (200C conventional). Transfer the filling to a deep baking tray,such as one suitable for lasagne,and spread the corn topping over the top. Scatter with the remaining cheese and bake for 20 minutes,until the cheese is melted and golden. Allow to stand for 10 minutes and serve with the sour cream,lettuce,tomato,onion,coriander and Tabasco sauce.
Also tryAdam Liaw's Mexican corn