Finely mince the onion and carrot.

In a small bowl, whisk together water, chicken soup stock granules, sugar, oyster sauce, and soy sauce until well combined.

Heat a small amount of oil in a frying pan over medium heat.

Add the ground pork to the pan, spreading it out but avoid breaking it apart immediately to encourage browning.

Cook the pork until browned on one side, then flip it over.

Add the minced carrots and onions to the pan with the pork.

Continue cooking, slowly breaking the pork apart into smaller pieces as it cooks with the vegetables.

Pour the combined flavoring ingredients (water, chicken soup stock, sugar, oyster sauce, and soy sauce mixture) over the pork and vegetables in the pan.

Bring the mixture to a simmer and continue to cook, allowing the sauce to reduce.

When the liquid has reduced to approximately 2/3 of its original volume, prepare a slurry of water and katakuriko (potato starch or cornstarch).

Gradually add the katakuriko slurry to the pan, stirring constantly, to thicken the sauce.

Continue to cook and stir slowly until all the liquid has cooked off, leaving a thick and glossy filling.