Watermelon Onigiri - Fun to make & delicious to eat, watermelon onigiri are the perfect summer bento box or picnic lunch item! Learn how to make these adorable summer rice balls by visiting (includes video tutorial!)

Watermelon Onigiri

  • Author: Shannon
  • Yield: 2 - 3 Onigiri
  • Category: Onigiri


Watermelon onigiri are the quintessential summer treat! Learn exactly how to make these fun & easy rice balls with step-by-step instructions.


Food Items:

  • 2 cups cooked Japanese short-grain rice, divided into 1.25 cups & 3/4 cup portions
  • 1/8 teaspoon beet powder
  • 1/8 – 1/4 teaspoon matcha powder
  • Black sesame seeds

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Pink Rice:

  1. In a small bowl, mix together beet powder and 2 – 3 tablespoons of warm water. Mix until fully dissolved.
  2. Add beet powder mixture to 1.25 cups of warm sushi rice, and mix until evenly incorporated. Set aside.

Green Rice:

  1. In another small bowl, mix together matcha powder and 2 – 3 tablespoons of warm water. Mix until fully dissolved.
  2. Add matcha mixture to 3/4 cup of warm sushi rice, and mix until evenly incorporated.

Watermelon Onigiri:

  1. With a damp paper towel, wipe the inside of your onigiri mold until it’s completely damp.  Fill 3/4 of the triangle with the pink rice, making sure to press down lightly with the handle of a rice paddle or spoon. Make sure you leave the bottom of the triangle empty, and have a clear, relatively flat dividing line formed.
  2. In the empty space left at the bottom of the triangle, add the green rice, pressing down with the back of a rice paddle, spoon, or chopstick to ensure it fills all the crevices.
  3. Once your onigiri mold is filled up just past the halfway point, insert the removable top piece and push until it’s fully inserted into the mold. Remove the top piece, and flip the rice mold over, making sure to do this over top of a plate covered in plastic wrap. If your rice mold has little push indents on the bottom, push it gently with your thumb, then gently tap the bottom and sides of the mold until the onigiri slides out.
  4. Using tweezers, add black sesame seeds to the pink portion of the onigiri – these are the black watermelon seeds. I used about 10 for a single watermelon onigiri.
  5. Repeat all steps until you’ve used up all your rice. Wrap your onigiri in plastic wrap until ready to serve.

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