Gather all the ingredients. You can make Awase Dashi with a convenient dashi packet in 3 minutes or from scratch in 20 minutes. Vegan Dashi takes 30 minutes to make. If you have time, consider making cold brew Awase Dashi or Vegan Dashi in advance.
Boil water in a saucepan (I used a 3-QT yukihira stainless steel pot) that‘s big enough to fit 8 ganmodoki later. Now, blanch 1 oz komatsuna for 15–30 seconds, first adding the stem ends that take longer to cook.
Remove the leaves from the boiling water and shock them in ice water to stop the cooking. Save the boiling water in the pot to use later.
Collect the komatsuna neatly by the stems and squeeze out the water. Cut into 1½-inch (3.8 cm) pieces and set aside.
In a pot (I used a 2.75-QT Staub round pot), combine 2 cups dashi (Japanese soup stock) and 1½ Tbsp sugar. Mix and set aside.
In the same boiling water you used to blanch the komatsuna, parboil 8 ganmodoki (Japanese fried tofu patties) for 10–15 seconds to remove any excess oil. Tip: If you‘re using ganmodoki from the freezer, you can add them frozen without thawing first.
Transfer the ganmodoki to the pot with the dashi using a fine-mesh strainer. Then, turn on the heat to medium and bring it to a simmer.
Once simmering, skim the scum and foam from the surface. Simmer gently, uncovered, for 15 minutes.
After 15 minutes, add 2 Tbsp soy sauce and 2 Tbsp mirin. Optionally, you can add 1 pinch Diamond Crystal kosher salt, but I didn‘t use any this time. Stir gently, then simmer for another 10 minutes. The Simmered Ganmodoki is now ready to serve. Alternatively, you can turn off the heat and let it cool on the countertop. Tip: Like other Japanese simmered foods (nimono), letting this dish cool in the broth allows the savory dashi flavors to soak into the patties.
Serve the Simmered Ganmodoki hot in individual bowls. Reheat it if you let it cool in the previous step, but make sure not to overcook it.
Ladle a small amount of the simmering broth into each bowl. Garnish with yuzu zest and the blanched komatsuna. Enjoy!
You can keep the leftovers in an airtight container and store for 3 days in the refrigerator or for up to a month in the freezer. Do not freeze previously frozen ganmodoki. Reheat the leftovers before serving, but do not overcook it.