Method

1. Place rice in a sieve and rinse under cold running water for 5 minutes. Put the rice to a medium saucepan, pour over 4 cups of water. Cover, bring to the boil and cook for 10 minutes until most of the water is absorbed. Remove from the heat and stand covered for 15 minutes.
2. Combine vinegar, sugar and salt in a small bowl. Spread cooked rice over the base of a large flat shallow non-metallic dish and sprinkle with vinegar mixture. Combine with a spatula, and leave until cool to touch. It should be sticky but not gluggy.
3. Lay the seaweed on a flat board. Spoon over a portion of rice, covering three-quarters of the sheet. Spread a spoonful of Marmite™, in a line down one side, over the rice using the back of a spoon. Top with a little carrot, avocado and cucumber.
4. Dampen the long edge of the seaweed with a little water. Roll up the sushi and seal the edges. Take a sharp knife and cut into 6 slices. Wet the blade between each slice, to stop from sticking. Repeat with all sheets of seaweed.