Very popular in Japan right now are onigirazu, a flattened onigiri (rice ball) sandwich. These were introduced more than 25 years ago by manga artist Tochi Ueyama in his ‘Cooking Papa’ series, which we just happened to have copies of in the guesthouse where we lived in Japan.
More substantial than a simple rice ball, the filling possibilities are endless, egg, tuna mayo, hamburger, tonkatsu matched with any cooked or raw vegetables.Cut open, they look lovely lined up in a box. This is one of my favourites. 
Salmon and Avocado Onigirazu
  • 4 sheets of nori
  • 4 bowls of recently cooked Japanese rice (short grain)
  • 4 tbs gomashio (ground, toasted sesame seeds mixed with a little salt)
  • 2 fillets of poached salmon, cooled (grilled works fine, too but will be drier)
  • 2 avocados, sliced long ways
  • 6 cm piece cucumber, finely julienned, 3cm long
  • 4 – 5 lettuce leaves, roughly torn
  • 4 tbs mayonnaise
  • 2 tsp ume paste, optional
Makes 4 (8 halves)
  • On a chopping board lay out a large square of cling film and place a nori sheet on top, turn so it is in a diamond shape
  • Place the equivalent of half a bowl of rice in the middle and shape into a rough square; flatten. You should have a small square with four triangles of nori showing
  • Sprinkle 1 tbs gomashio over the rice
  • Flake half of one salmon fillet over to cover the rice
  • Layer the avocado, then cucumber on top
  • Mix the mayo with the ume paste and spread a quarter over the cucumber, then cover with lettuce leaves
  • Cover with the remaining rice, keeping the square shape as much as possible
  • Now, fold the two opposing triangles of nori in over the rice, then the final two to make a small, square parcel
  • Bring the cling film corners over to wrap and secure
  • Wait till the rice has cooled before cutting in half with a sharp, wet knife
  • Repeat and place the onigirazu halves filling side up in a box

A little bit more…

  • You can use either brown or white rice, but it needs to be short grain. Pudding rice works well if you can’t find regular Japanese or sushi rice
  • The other fillings pictured are smoked mackerel, red pepper, and rocket with mayonnaise, and shredded egg, wakame and fermented ginger carrot
  • The difference between sushi and onigiri and onigirazu is the rice. Sushi rice is seasoned with vinegar, salt and sugar (or alternative) whereas onigiri or onigirazu uses plain rice. 
  • Cling film/saran wrap makes them easier to assemble and transport but I just use a sushi mat or clean tea towel to wrap them in