Gather all the ingredients.

In a small bowl, whisk together the ingredients for the sauce: 1 Tbsp soy sauce, 1 Tbsp sugar, 1 Tbsp mirin, 2 tsp rice vinegar (unseasoned), and ½ tsp potato starch or cornstarch. Set aside.

Wrap 5 oz medium-firm tofu (momen dofu) with a paper towel and let it drain for 15 minutes.

Meanwhile, remove the seeds from 3 oz sweet bell peppers under running water and dry completely.

Mince the sweet bell peppers and chop 1 green onion/scallion finely. Grate the ginger and measure 1 tsp ginger (grated, with juice).

In a large bowl, combine 14 oz ground chicken, the minced sweet bell peppers, and the chopped green onion. Break the drained tofu into small pieces and add to the bowl.

Add 1 large egg (50 g each w/o shell) and mix it all together.

Add the grated ginger, ½ tsp Diamond Crystal kosher salt, and ⅛ tsp freshly ground black pepper and combine well.

Using two tablespoons or a cookie scoop, form small meatballs. I usually scoop the meatballs straight into the frying pan (see the next step).

Heat a nonstick frying pan over medium heat. Add 1 Tbsp neutral oil. When hot, add the meatballs, keeping some space between each. Cook in batches, if necessary.

When the bottom is nicely browned, flip them over. Cover with the lid to cook until the inside is no longer pink, about 3 minutes. Reduce the heat to medium low if they are browning too fast. Transfer to a plate and cook the remaining batch(es).

When the meat in the last batch is cooked through, add the other cooked meatballs and their juices back into the pan.

Pour the sauce over the meatballs. Simmer to reduce and thicken the sauce while flipping the meatballs to coat both sides with the sauce.

Keep the leftovers in an airtight container with the sauce, let cool completely, and keep in the refrigerator for up to 3 days and in the freezer for a month.