Heat oil in a frying pan over a medium-high heat, add onions and cook, stirring occasionally, for 5 minutes or until starting to brown.Add garlic and cook for 30 seconds.Add mince and cook, breaking up with a wooden spoon for 6- 8 minutes or until brown.Add tomato paste, stock and ½ a cup of water and bring to a simmer.Add rice, reduce heat to medium-low and cook uncovered for 8-10 minutes or until all the liquid is absorbed.Place in a bowl and top with avocado.