For the Sushi Rice
For the Sushi Vinegar
80ml rice vinegar
3tbsp. caster sugar
To Assemble the Onigirazu
For the Sweet Potato and Omelette Filling
1 medium/ large sweet potato, peeled
2 tbsp soy sauce
½ tsp sesame oil
1 tsp rice vinegar
1 tsp mirin
1 tsp vegetable oil
2 eggs, lightly beaten
½ red pepper, thinly sliced, lengthwise
Pickled ginger slices
Kewpie mayonnaise (Japanese mayonnaise)
For the Salmon and Avocado Filling
100g smoked salmon
A handful of baby spinach leaves
1 ripe avocado, peeled and thinly sliced
For the sushi rice, place the rice in a large bowl, rinse with cold water and drain. Repeat this process about four times to remove as much of the starch as possible. Leave now to soak for 30 minutes and then drain and rinse well. Transfer the rice into a solid steam container and add enough cold water to cover by 1cm above. Steam at 100C for 16 minutes.
Meanwhile, combine the ingredients for the sushi vinegar into a small saucepan over a medium heat and whisk gently to dissolve the sugar and salt. Set aside to cool.
Place the steamed rice into a large, shallow bowl. Put a quantity of ice cubes into another bowl of similar size and sit the bowl of rice on the ice. Gradually pour in the sushi vinegar and mix with a large spatula, cutting through the lumps of rice. Do not stir or else the rice will become crushed and lumpy. Fan the rice with the other hand while continuing to cut through with the spatula until the rice cools to room temperature. The rice will be shiny and sticky but each grain will be separate. Cover with a damp cloth and set aside.
For the sweet potato filling, preheat a Miele Oven on Fan plus, 210°C. Cut through the middle of the sweet potato to make ½cm thick discs. In a small bowl, mix together the soy sauce, sesame oil, rice vinegar, mirin and vegetable oil to make a marinade. Generously brush both sides of the sweet potato discs with the marinade and place on a sheet of non-stick paper on a baking tray. Put the tray in the oven and bake the sweet potato for 20 minutes turning them over after 10 minutes. Set aside to cool and season lightly with a little salt.
Heat a little vegetable oil in a small omelette pan and pour in the beaten egg. Cook gently to make a small flat omelette. Remove from the heat and allow to cool.
To assemble the onigirazu, put a square of cling film slightly larger than the nori sheet on to the work surface and then place the nori sheet on top, shiny side down and rotated 45° in relation to the cling film. Wet your hands (keep a small bowl of water handy) and take a small handful of rice. Place it in the middle of the nori sheet and shape it into a 9cm square keeping the layer of rice as even and compacted as possible.
For the sweet potato filling, drizzle a little kewpie mayonnaise over the rice and top with a thin layer of pickled ginger, place on a sweet potato slice then cut a square out of the omelette and place on top of the sweet potato. Top with the slices of red pepper. Drizzle over some of the okonomiyaki sauce. Finish with a final layer of sushi rice.
Dampen the edges of the nori sheet and fold in all four corners to make a wrapping over the rice. The finished result will look like a small parcel. Finally, gather up the cling film fairly tightly around the sandwich. Put something reasonably heavy (like a small breadboard) on the onigirazu to compress it slightly. Leave for 15 minutes to let the seaweed soften. When ready to eat, remove the cling film and cut the onigirazu in half or thick slices.