Cook rice. (details on how to cook rice are from the link in the recipe tip above)
Make seasoned vinegar. Put vinegar(50ml), sugar (2 tablespoon) and salt (1 teaspoon) in a small bowl and mix well.
Put hot cooked rice in a large bowl, sprinkle seasoned vinegar over the rice, and mix with a large spoon or spatula. Cover with a tightly squeezed wet cloth or kitchen paper and allow the rice to cool to a slightly warmer temperature.
Prepare scrambled eggs and stir-fried beef while the rice is cooling. To make scrambled egg with microwave oven: put eggs and a pinch of salt in microwave safe bowl. Then make a beaten egg. Put the bowl in the microwave oven and cook for 1.5 minutes with 750w. Take the bowl out from the microwave oven and stir with a whisk. Put it back in the microwave oven and cook 15 - 30 seconds again. Remove the bowl from oven and stir with a whisk. This repeats until the egg mixture becomes scrambled egg. Be careful not to overcook. If you cook too long, the some part of the eggs will turn grayish.
Heat vegetable oil in a frying pan over medium heat. Add the beef and fry until the beef turned to brown. Then add seasoning (2.5~3 tablespoon soy sauce, 2,5~3 tablespoon sugar, 1 tablespoon Japanese sake), fry until the juice is gone and remove from the heat.
Gently mix half of the baby leaves with cooled vinegared rice. Place this in a large bowl or plate. Then put the rest of the baby leaves on top.
Sprinkle scrambled egg over baby leaves.
Finally, place the beef in the middle and sprinkle with white sesame seeds to complete.
Notes
You can serve 4 people on a large plate, or you can serve each plate separately.