Wash the rice well and drain. Cover with the measured water and bring to a simmer. Cover and cook for 12 minutes then leave to sit for 5 minutes with the lid on.
Meanwhile, heat the vinegar, sugar, and salt until dissolved then leave to cool. Turn the cooked rice out onto a flat tray to cool. When cool, place in a bowl, stir in the vinegar solution, and mix with a wooden spoon.
Lay half a sheet of nori seaweed onto a rolling mat. Dip your hand in cold water and quickly place a handful of rice in a line along the seaweed. Flatten out with your fingertips using the water to stop any sticking. The key is to do this quickly. The rice should cover half the width of the sheet so now you can place your combo of filling in the middle of the rice. Use the mat to roll up the sushi roll, pinch and squeeze the mat to shape it into a round cigar shape. Practice makes perfect!
Slice into inch-thick rolls with a sharp knife, turn onto their sides so the rice is facing upwards, and serve with the pickled ginger and wasabi mixed with soy sauce.