Onigirazu (tuna sushi sandwiches with pickled radish)

Instructions

1. Cook the grains Combine the brown rice, quinoa and wild rice a saucepan, rinse thoroughly and drain well. Add 1½ cups water. Place over medium-high heat, cover with a lid slightly ajar and bring to the boil, then reduce to medium and cook for about 30 minutes or until the grains are tender. Turn off heat, fluff the grains with a fork, wrap the saucepan lid in a tea towel, then place securely on the pan and let grains steam for 10 minutes.
   
   
2. For the pickled radish, place the vinegar and sugar in a small saucepan, bring to the boil and gently boil for 5 minutes. Set aside and cool slightly. Pack the radish, ginger and peppercorns into a 1-litre (4-cup capacity) glass jar. Pour over the vinegar and set aside to pickle while you make the onigirazu. Seal with a lid and refrigerate the remainder for up to 1 week.
   
   
3. Combine the vinegar and sugar and stir to dissolve. Place the grains in a large mixing bowl. Add the vinegar mixture and using a large wooden spoon, stir the grains gently and continuously, allowing the steam to escape, until the grains have cooled.
   
   
4. Place a 30 cm square of plastic wrap on a work surface. Place a sheet of nori in the centre like a diamond. Take ¼ cup grains and, using the base of the cup measure, pat into a 10 cm square in the centre of the diamond - this is important for folding. Pat the square so its compact and neat.
   
   
5. Arrange a slightly overlapping layer of pickled radish on top of the grains. Arrange a single layer of cucumber, then 3 tuna slices, then a single layer of avocado. Season with sea salt and togarashi, then drizzle over a generous amount of mayonnaise. Arrange another slightly overlapping layer of pickled radish on top.
   
   
6. On a 13 cm square of baking paper, take ¼ cup grains and, using the base of the cup measure, pat into a 10 cm square. Quickly flip the grains onto the top of the stack, peel off the baking paper and clean up any loose grains.
   
   
7. Tightly fold the bottom point of the nori diamond up over the filling, then the right point over the filling, then the top point and then the last point to make a neat, compact square. It helps if you have one hand holding the nori over the filling, keeping everything secure, while the other hand tightly folds in the other nori points. 
   
   
8. Wrap the onigirazu in the plastic wrap so its tight and compact and weight down with a plate for 5-10 minutes. This allows the nori to soften. 
   
   
9. Repeat with the remaining ingredients.
   
   
10. Unwrap the onigirazu and, using a sharp knife, cut in half.