While the rice is cooking, cut the fillings into long, narrow strips, creating two different combinations.

Place a sheet of nori on a cutting board with the long side facing you.

Spread 1/2 cup of warm rice on the bottom one-third of the nori sheet.

Sprinkle the rice with a little vinegar.

Place three fillings on the rice, forming three narrow rows across the width of the rice.

Gently press the filling into the rice.

Starting at the edge near you, roll the nori away from you, enclosing the fillings and forming a tube.

Make the nori roll tight and secure.

If the end of the sheet does not stick tightly, dampen the edge with a little water and seal well.

Repeat until all nori sheets have been filled and rolled.

At this point, rolls can be chilled for later use.

With a sharp knife, cut the nori roll into 1-inch pieces.

Serve with vinegar soy or mustard sauce