Beat the eggs together with the mirin, soy sauce, salt and 1 tsp of the sesame oil.
Heat a small frying pan with the remaining sesame oil until just hot - not too hot, we don't want the egg to cook too quickly as it'll be rubbery.
Pour the eggs into the pan and leave for a few seconds before stirring. Stir until just set, but still wet - it will continue cook in the pan.
Heat (microwave) the rice in a bowl(I like to sprinkle over a couple of tablespoons of water to my leftover ice before microwaving, to keep it moist and avoid drying out).
Spoon over the eggs and then sprinkle with the spring onion and a little seaweed