If you own a rice cooker, use the sushi rice or white rice setting according to the manufacturer's recommendations.
For standard cooking, combine water and rice in a medium saucepan. Bring to the boil on medium, then reduce heat to low. Simmer with a lid for 12-15 minutes until tender.
Remove rice from heat, cover and leave to rest for 10 minutes. After resting, stir in rice vinegar, garlic powder, sugar and salt. Set aside and keep warm.
Slice and prepare the cucumber, carrot, avocado and garnishes for when the breast steaks are cooked.
Heat oil in a pan over medium heat. Add steaks and cook for 7-10 minutes on each side, turning occasionally until lightly coloured. Allow to rest before slicing.
Spoon the desired serve of rice into bowls. Top with chicken, cucumber, carrot, avocado. Finish with a splash of soy sauce and garnish with sesame seeds.