Heat oil in a large frying pan over high heat. Add the onion and garlic to the pan and cook for 4-5 minutes or until golden. Add the spices and mix.
Add the mince and break it up with the back of a spoon, cooking for 5-6 minutes or until brown. Add the tomato paste, tinned tomatoes, 1⁄2 cup water, salt and pepper. Simmer on medium heat for 12 – 15 minutes or until reduced.
Preheat a chargrill pan to high heat. Add a round piece of baking paper to the pan. Brush the avocado halves with oil and chargrill the cut side for 2 minutes or until lightly charred.
To serve, divide the mince, cheese, lettuce and tomatoes between each avocado half. Serve with sour cream, chilli and coriander.