Rinse the uncooked sushi rice until cold water until the water runs clear.
Place the water into a saucepan and bring to the boil.
Add the rice and cook until soft and all the water has been absorbed.
In another saucepan, add the rice vinegar, oil, sugar and salt and bring to the boil.
Remove the cooked rice from the saucepan, allow to cool slightly for 5 minutes before stirring through the rice vinegar mixture. Try to incorporate as much air as possible when folding through the vinegar mixture.
Once combined, place the sushi rive into a baking tray and flatten.
Press the rice down firmly and place it into the fridge to set.
Once set, cut the pressed sushi rice into small 10cm x 10cm squares and remove from the tray.
Place the squares into a medium heated pan with the melted butter and gently fry until golden brown and crispy on both sides.
Set aside to top with the toppings.