Ultimate Guide to Making Delicious Hijiki Onigiri at Home

Imagine tucking into a delightful bundle of flavors, where every bite offers a mix of salty, sweet, and umami — that’s the magic of Hijiki Onigiri. This traditional Japanese snack transforms simple ingredients into a portable feast that’s as nutritious as it is delicious. Originating from the land of sushi and sakura, onigiri is a popular comfort food, often filled with a variety of ingredients, but hijiki, with its mineral-rich, slightly chewy seaweed, makes these rice balls uniquely satisfying.


Here’s what you’ll need to create your very own Hijiki Onigiri, blending the perfect mix of flavors and textures for a satisfying snack.

Hijiki Seaweed Preparation

  • Dried Hijiki Seaweed: 1/4 cup
  • Water: Enough to soak
  • Soy Sauce: 1 tablespoon
  • Mirin: 1 tablespoon
  • Sugar: 1 teaspoon

First, soak the dried hijiki seaweed in water for about 30 minutes to rehydrate it. Once it’s softened, drain the water. In a small saucepan, mix the soy sauce, mirin, and sugar. Add the hijiki and cook over low heat for about 10 minutes until the flavors are well absorbed. Set aside to cool.

Rice Cooking

  • Short-Grain Rice or Sushi Rice: 2 cups
  • Water: 2 1/2 cups
  • Salt: A pinch

Wash the rice until the water runs clear. This usually takes about 2-3 rinses. In a rice cooker or a pot, add the washed rice, water, and a pinch of salt. If you’re using a pot, bring to a boil, then reduce the heat to low, cover, and simmer for 18 minutes. Remove from heat and let it sit, still covered, for 10 more minutes to steam. Fluff the rice with a fork or a rice paddle afterward.

  • Cooked Salmon Flakes: 1/4 cup
  • Pickled Plum (Umeboshi), finely chopped: 2 plums
  • Scallions, finely chopped: 2 tablespoons

For a variety of flavors, you can include cooked salmon flakes, which add a rich, umami taste, or finely chopped pickled plums for a tart and zesty punch. Scallions provide a nice crispy contrast. Prepare these ingredients so they are ready to mix into or accompany your rice and hijiki mixture.

Equipment Needed

To prepare Hijiki Onigiri, the right tools make the process smoother and ensure your rice balls turn out perfectly shaped and delicious. Here’s what you’ll need:

  • Rice Cooker: A staple in most kitchens that prepare rice regularly. This will help you cook the rice evenly, ensuring the perfect texture for onigiri.
  • Medium Saucepan: You will need this for cooking the hijiki seaweed with the seasonings like soy sauce, mirin, and sugar. Choose one with a heavy bottom to prevent burning.
  • Mixing Bowls: Have a few on hand for mixing the hijiki seasonings and for tossing the rice with the hijiki mixture.
  • Wooden Spoon or Rice Paddle: Essential for fluffing and mixing the rice without smashing the grains.
  • Onigiri Molds or Plastic Wrap: Whether you choose to shape your onigiri by hand or with molds, these tools will assist in forming them into the traditional triangular shape.
  • Measuring Cups and Spoons: To accurately measure your ingredients like rice, water, soy sauce, mirin, and sugar, ensuring the flavor balance is perfect.
  • Cutting Board and Knife: Needed for finely chopping ingredients like scallions and any additional fillings you choose to incorporate.

Collect these items before starting, and you’ll find making Hijiki Onigiri to be a seamless and enjoyable experience.

Preparation Steps

Now that you have all your ingredients and equipment ready, let’s dive into the preparation steps for making your Hijiki Onigiri. Follow these steps closely to ensure your onigiri turns out delicious and holds together well.

Soaking Hijiki Seaweed

First, measure out about 1/4 cup of dried hijiki seaweed. Place the hijiki in a small bowl and cover it with plenty of water, as it will expand significantly. Let it soak for about 30 minutes until it’s fully rehydrated and has increased in volume. Once soaked, drain the hijiki and give it a quick rinse under cold water to remove any grit or excess salt.

Cooking Rice

Begin by rinsing 2 cups of short-grain sushi rice under cold water until the water runs clear. This removes excess starch and helps the rice to become more sticky, which is perfect for onigiri. After rinsing, let the rice drain in a colander for a few minutes. Transfer the rinsed rice to your rice cooker and add 2 1/4 cups of water. Stir gently to ensure the rice is evenly distributed. Set your rice cooker to the “sushi rice” setting and start cooking. Once the rice is cooked, let it sit in the rice cooker for about 10 minutes before fluffing it with a rice paddle or wooden spoon.

Preparing Additional Fillings

While your rice is cooking, you can prepare the fillings for your Hijiki Onigiri. In a small bowl, mix together the rehydrated hijiki with 1 tablespoon of soy sauce, 1 tablespoon of mirin, and 1 teaspoon of sugar. Stir this mixture well and let it marinate for a few minutes to absorb the flavors. Additionally, prepare any other fillings you like, such as flaking cooked salmon with a fork or chopping a pickled plum into small pieces. If you’re using scallions, finely chop them and set aside to sprinkle on your onigiri for an extra burst of freshness.

Assembling Hijiki Onigiri

Now that your ingredients are prepared and ready, assembling your Hijiki Onigiri is where the magic happens. This process combines tradition with personal touch, allowing you to shape and fill the rice balls according to your taste.

Shaping the Onigiri

  1. Begin by wetting your hands with water to prevent the rice from sticking. Sprinkle a little salt on your palms for added flavor.
  2. Grab about a half cup of the seasoned rice and form it into a mound in one hand.
  3. Gently press the rice between your palms, forming it into a triangular, round, or oval shape, based on your preference. Be firm enough to compress the rice so it holds together, but gentle enough to avoid mashing the grains.

Filling the and Shaping the Hijiki Onigiri

  1. Once you have the base shape, make a small indentation in the center of the mound using your thumb.
  2. Place a spoonful of your choice of filling into the indentation. Popular options include the marinated hijiki mixture, cooked salmon flakes, or a piece of pickled plum.
  3. Carefully cover the filling with a bit more rice, and then re-shape the onigiri as needed to ensure the filling is completely enclosed.
  4. Repeat the process until all your rice and fillings are used. Each onigiri can be wrapped with a strip of nori seaweed or left unwrapped according to your preference.
  5. Serve the hijiki onigiri immediately, or wrap them in plastic wrap to keep them fresh for a delicious treat later.

With these simple steps, you’ve transformed humble ingredients into delicious and visually appealing Hijiki Onigiri. Enjoy sharing this delightful snack with friends or as a satisfying solo treat.

Serving Suggestions

Once you’ve mastered the art of making Hijiki Onigiri, the next exciting step is serving them in a way that complements their distinct flavors and textures. Here’s how you can turn the simple act of serving these rice balls into an enjoyable part of your meal experience.

Pair With Japanese Soup

Serve your Hijiki Onigiri alongside a bowl of Miso soup or a clear Dashi-based broth. The light and soothing taste of these soups balances the savory richness of the onigiri, providing a comforting meal combination.

Offer a Variety of Condiments

Place small dishes of additional condiments on the table to enhance the flavors. Some popular options include:

  • Soy sauce for a salty kick
  • Wasabi for a touch of heat
  • Pickled ginger for a refreshing zing

These condiments allow each person to customize their onigiri experience according to their taste preferences.

Include Side Salads

Accompany your Hijiki Onigiri with a side of Japanese salads such as Sunomono (vinegared cucumber salad) or a seaweed salad. These light and crisp salads offer a delightful contrast to the denser, chewy texture of the onigiri.

Presentation Tips

Present your Hijiki Onigiri on a traditional Japanese wooden platter or a simple ceramic dish to enhance their visual appeal. If entertaining guests, you might also consider using individual plates with a single onigiri and a selection of accompaniments for a personalized touch.

Beverage Pairings

For beverages, serve either a cup of green tea which harmonizes with the subtle flavors of the rice and hijiki, or a light, crisp Japanese beer to cut through the richness and refresh the palate.

Make-Ahead and Storage Tips

After enjoying the art of making Hijiki Onigiri and exploring various serving suggestions, you might wonder how best to handle leftovers or make them ahead of time for future enjoyment. Here are tips on how to keep your Hijiki Onigiri fresh and delicious:

Preparing in Advance

If you plan to prepare Hijiki Onigiri in advance, there’s a strategy to keeping the rice fresh and the seaweed crisp. Shape your rice balls without adding the hijiki or any other wet ingredients to the center. Wrap each rice ball tightly in plastic wrap and store them in the refrigerator for up to two days. When ready to serve, reheat the rice balls gently in a microwave, then mix in the hijiki seaweed to maintain its texture and flavor.

Storing Leftovers

Hijiki Onigiri can be stored in the refrigerator if you have leftovers. Place the rice balls in an airtight container or wrap them individually in plastic wrap. They will stay fresh for about 24-48 hours. Remember, the rice may harden slightly when cold, so it is best to bring them to room temperature or warm them slightly in the microwave before serving.

Freezing for Long-Term Storage

For those who like to batch cook or need to store Hijiki Onigiri for an extended period, freezing is an option. Wrap each rice ball individually with plastic wrap and then place them in a freezer bag, squeezing out as much air as possible before sealing. Hijiki Onigiri can be frozen for up to one month. To serve, thaw them in the refrigerator overnight and then warm them up gently in the microwave. This method ensures that you enjoy your meal as if it were just made.


So there you have it! You’re now equipped to dive into the delightful world of Hijiki Onigiri. Whether you’re crafting these tasty treats for a quick snack or a unique addition to your meal it’s clear they offer a versatile and enjoyable experience. Remember the joy doesn’t end with the last bite—these onigiri are perfect for sharing with friends and family. So why not impress your loved ones with your new culinary skills? Grab your ingredients and get rolling. Your next delicious adventure with Hijiki Onigiri awaits!

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