Soak and wash the rice several times until the water runs clear. Drain the water and transfer the rice into a pot. Add 200 ml water, cover, and cook over high heat for five minutes. Then reduce the heat to simmer for five minutes. Finally, turn the heat off and leave the rice to cook in its steam for another five minutes.
While the rice is cooking, de-seed and finely chop red chilli.
Finely chop the spring onions.
Cut the avocado in half and remove the seed. Score the avocado into small dice, then scoop it out of the skin into a bowl. Lightly mash the avocado. Please do the same for the other half, but don't mash it. This will leave some texture in the smashed avocado.
Add chopped spring onion, red chilli, soy sauce and lime juice and give it a good mix and refrigerate.
Once the rice has cooked and steamed, remove it from the pot into a large bowl to stop it from cooking further. Add the sushi vinegar and mix well to combine. Set aside to cool.
Prepare a bowl of water and a sushi mat for rolling.
Wet your hands, scoop up rice, shape it into a ball, and transfer it to the centre of the sushi mat. Roll the end of the mat (the end nearest to you ) to cover the rice. Now pull the rolled-over mat towards you using both hands to form a bar of sushi rice with a square profile. Use an equal amount of pressure while pulling. Press the rice inwards from the sides to ensure a tight rice bar. As you pinch and roll, the rice will take on a slightly square shape. Keep pinching and rolling until you have a tight bar of rice. Repeat with the rest of the rice.
Wet a sharp or serrated knife and cut the rice rolls into cubes, the width shouldn't be more than the width of your finger. Wet the knife each time you cut or else the rice will stick to the knife and break off sushi rice bar. Wash the knife if required to remove the stickiness. Repeat with all the rice bars until you have about 24 cubes.
Heat the oil in a large pot or pan for deep frying.
Fry the rice cubes a few at a time to ensure they don't stick together. Fry each side until golden brown and crispy. Repeat with all squares, and drain excess oil onto a kitchen towel.
To assemble, add a spoonful of avocado mix to each cube. Garnish as desired with either chilli or spring onion. Serve immediately.