HEAT the oil in a large saucepan and sauté the onion for 5 minutes or until softened. Add the beef and cook for 5-8 minutes or until lightly browned. Add the tomatoes, beans, VEGEMITE, tomato paste, cocoa, chilli flakes and water. Stir to combine and simmer gently for 20-30 minutes or until thickened.
TOSS together the red onion, avocado, tomatoes and coriander. Spoon the beef into serving bowls and serve with the salsa and some corn chips. Serve immediately.