Make one long cut along the length of the fish sauce. It should be about 7 mm deep. This will be the cleft in the heart.
Cut diagonally towards the long cut on both sides of the cut.
Cut off the opposite part of the fish sauce to make the point of the heart, matching up with the cleft.
Shave off any sharp edges to make a rounded heart. (It's OK if it's a bit crooked.)
Wrap the sausage with a nori sheet cut in half. Make sure to stick the nori securely in the cleft.
Mix the iri tamago (fine scrambled eggs) into the warm rice. You can add anything else as long as its color coordinates well with the sausage, such as chopped pickled vegetables.
Spread a piece of plastic wrap on a sushi mat, and put a sheet of nori on that. Spread the rice evenly over the nori.
Put the heart shaped sausage in the middle and roll it up. Neaten up the roll over the plastic wrap, and leave to cool.
When the roll has completely cooled, cut it up wrap and all, Peel off the wrap and put on a serving plate to finish.
Story Behind this Recipe
This uses cheap ingredients and is easy to make, but children love it.
A fish sausage that's about 2 cm in diameter will look better and be easier to handle. In Step 5, the key is to wrap just the sausage with nori seaweed. Even if the heart is a bit crooked, the black outline will make it look nice.