First of all, get your rice on to cook (instructions for perfect short-grain rice are here) and toast up some sesame seeds. Also immerse some wakame seaweed in cold water to rehydrate.
Now mix 4 eggs, 4 tsp sugar, 2 tsp sake, 4 tsp corn flour and a large pinch of salt together in a bowl with a fork. Heat up a small frying pan over a low heat and wipe it with oil, when it's hot pour in a small amount of the egg mixture - about a quarter. Keep these omelettes fairly thin.
When the egg has set, flip the omelette over and cook for a minute on the other side before turning out onto a plate. Repeat until you have at least 4 omelettes, but you'll probably get 5 which means one to eat hot right out of the pan!
When your rice is done, turn it out into a glass bowl with a tbsp of rice vinegar. Fan the rice with one hand while turning and stirring it and the vinegar with a spatula in the other. The rice should go very sticky. Add the toasted sesame seeds and mix through, then leave to one side to cool down.
The salad is very easy to put together. Peel a cucumber and rub salt into the surface, massage it for a few minutes over the sink to firm up the flesh and season it. Then slice it into half moons.
Mix the cucumber with the drained seaweed and the smoked salmon, if using. Whisk up a splash of rice vinegar, a drizzle of toasted sesame oil, a pinch of sugar, black pepper and some shoyu (Japanese soy sauce) to taste.
When the seasoned sesame rice is relatively cool, place a large spoonful in the center of each omelette and fold around into a square. Lay down with the folds on the bottom and sprinkle over some furikake or pickled ginger. Serve with the salad.