Combine 2 cups (500ml) water and the tomato paste in a large jug and whisk until the paste is dissolved.
Heat the oil in a large saucepan over medium heat. Cook the onion and garlic, stirring, for 5 minutes or until softened. Increase the heat to high and cook the beef, stirring with a wooden spoon to break up any lumps, for 2 minutes or until browned. Stir in the spices and cook for 1 minute or until fragrant. Add the rice and stir over medium heat until well coated in oil and spices. Add the tomato paste mixture and the beans and stir well. Season. Bring to the boil over medium-high heat. Cover and reduce the heat to medium. Cook, covered, for 15 minutes. Remove from the heat and stand, covered, for 5 minutes.
Meanwhile, combine the corn, avocado, cucumber, coriander sprigs and chilli in a medium bowl. Sprinkle the Mexican rice with the corn salsa and serve with the lime wedges and a dollop of yoghurt.