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Rice Balls with Three Kinds of Toppings (Summer Version)


At our last Summer Festival at TOIRO, we made hundreds of onigiri (rice balls) with freshly made rice in our double-lid donabe rice cooker, Kamado-san, and served with these summer-theme toppings. We were so happy many of our guests kept coming back to try more.

The Walnut Miso include Fig Vinegar so it has a refreshing soft acidity. The Slow-Roasted Tomato is rich in umami and the Smoked Soy Sauce adds the extra layer of complexity. The Roasted Corn and Yuzu-Kosho Mayo has beautiful sweet corn flavor with aromatic heat from the Yuzu-Kosho.

These toppings are also great to serve with cold tofu or grilled meat. So,hope you will try all three kinds. The amounts of these toppings in this recipe are more than enough to make the suggested servings, so you can keep any leftover for another use.


Double-lid donabe rice cooker, Kamado-san (3 rice-cup size)


4 - 5


(Onigiri Topping #1: Walnut & Fig Vinegar Miso) 

Makes about 1/2 cup

  • 1 oz (30 g) walnut halves
  • 2 tablespoons miso
  • 1/2 teaspoon raw brown sugar
  • 1 tablespoon fig vinegar
  • 1 tablespoon or more water


(Onigiri Topping #2: Slow-Roasted Tomato with Smoked Soy Sauce)

 Makes about 1/2 cup

  • 1 pound tomatoes (about 3 medium)
  • Sea Salt
  • Freshly-ground black pepper
  • Extra virgin olive oil
  • 2 - 3 teaspoons smoked soy sauce


(Onigiri Topping #3: Donabe-Roasted Corn and Yuzu-Kosho Mayo)

 Makes about 1 cup

(Equipment: Tagine-style donabe, Fukkura-san)

  •  1 ear medium corn
  • 1/4 cup mayonnaise
  • 1 tablespoon yuzu-kosho
  • Chopped cilantro


    Walnut & Fig Vinegar Miso

    1. Pre-heat the oven at 350 F (180 C). Spread the walnuts in a baking sheet and roast for 7 – 8 minutes or until the walnuts are lightly browned. Let them cool down.
    2. Combine the walnuts, miso, sugar, vinegar, and water in a food processor. Pulse until the contents become smooth paste. Add more water if necessary.

    *The walnut & fig vinegar miso can keep in refrigeratorfor up to 1 week.


    Slow-Roasted Tomato with Smoked Soy Sauce

    1. Pre-heat the oven at 300 F (150 C). *For convection oven, set the temperature at 250 F (125 C).
    2. Core each tomato and cut in half horizontally.
    3. Line a baking sheet with a piece of aluminum foil and place the tomatoes, cut side up.
    4. Season the open sides lightly with the salt and pepper.Lightly drizzle the olive oil and gently rub by hand.
    5. Roast the tomatoes in the oven for 4 – 5 hours or until they are about 2/3 of the original size (check every hour after 2 hours).
    6. Remove the tomatoes from the oven and let them cool down. Peel off the skin by hand (the skin should come off easily).
    7. Cut the tomatoes into small dice and season with the smoked soy sauce.

    Donabe-Roasted Corn and Yuzu-Kosho Mayo

    1. Set a metal grate in the Fukkura-san’s skillet (you can line the skillet with a pice of aluminum foil for easy cleaning, if you like). Arrange the corn on the grate. Cover with lid and set over medium-high heat. Cook for 20 – 25 minutes or until it’s cooked to your desired doneness. Meanwhile, rotate the corn a few times. Remove from the heat and let it cool down. Slice the kernels off the cob.
    2. Combine half of the kernels, mayonnaise, and yuzu-kosho in a food processor, and puree the mixture. Transfer to a bowl, add the remaining kernels and mix well with a spatula.
    3. Add some cilantro and mix again.

    About the measurements used in our recipes

    For rice measurement, traditional Japanese rice measurement is used.
    • 1 rice-cup = 3/4 US cup = 180 ml
    Other conversions (US to metric measures)
    • 1 cup = 240 ml
    • 1 inch (1") = 2.5 cm
    • 1 ounce (1 oz) = 30 ml