Let's prepare the lotus root. Thoroughly rinse the lotus root and grate it along with the skin. The grated root should make approximately 50g (1.8 oz).
Slice about 100g (3.5 oz) of the lotus root. Then, coarsely chop the slices into small pieces.
Let's make the sauce. Combine the vinegar, sake, sugar and soy sauce. Stir to dissolve.
Let's combine the meatball ingredients. In a large bowl, season the ground pork with the salt and pepper. Add the soy sauce and sake. With your hand, squish the mixture to combine the ingredients. Then, loosely spread your fingers forming a rake shape to thoroughly mix the meat until the mixture becomes sticky. This will make it easier to combine other ingredients later.
Add the chopped ginger root, coarsely chopped long green onion, grated lotus root, and coarsely chopped lotus root. Add in the potato starch and sesame oil. Squeeze the mixture so all ingredients are well incorporated. Even if you use lean meat, adding the grated lotus root will give it a tender texture. The crispy chopped lotus root also adds a pleasant texture to the dish.
When the meat mixture is thoroughly combined, shape them into balls about the size of ping pong balls and place them onto a plate. You'll have about 12 meatballs in total. Now, remove your kitchen glove. Wet your hands with vegetable oil and roll each meatball between your palms to make a smooth surface.
Let's cook the meatballs. Heat the oil in a pot to 170 °C (340 °F) and reduce the heat to low. Gently place the meatballs into the pot. Then, bring to medium heat. Don’t touch the meatballs until the surface firms up. Occasionally shake the pot to keep the bottom of the meatballs from burning.
When the surface firms up, turn the meatballs over. Keep turning them to brown evenly for 5 to 6 minutes. They will turn to a delicious golden brown color. Remove the meatballs and place them onto a cooling rack.
Let's coat the meatballs with the sauce. Heat another pot on medium heat. Stir the sauce and pour it into the pot. Bring it to a boil and reduce the sauce. When the sauce begins to thicken, add the meatballs. Coat the meatballs with the sauce.
Place the meatballs onto a plate along with the sweet and sour sauce.
You can also top with shichimi chili pepper, sansho pepper or a generous amount of chopped seasonal kinome leaves to taste.
The meatballs are great for adding to bentos but be sure to cool them before packing.
Finally, the meatballs can be refrigerated or frozen so you can always keep them on standby.