In a medium bowl, combine the ground chicken, soy sauce, fresh ginger, toasted sesame oil, and black pepper. Mix well until thoroughly combined.
Place about 2 teaspoons of the chicken filling onto the center of each dumpling wrapper. Moisten the edges of the wrapper with water, then fold the wrapper in half to create a half-moon shape, pressing to seal. You can also pleat the edges for a decorative finish.
To make the chili oil, heat the neutral oil in a small saucepan over medium heat. Add the minced garlic and cook until fragrant, about 30 seconds, being careful not to burn it.
Remove the saucepan from the heat and stir in the chili flakes and sugar. Let it steep for at least 10 minutes to infuse the flavors.
Bring a large pot of salted water to a boil. Carefully add the dumplings and cook for 3-5 minutes, or until they float to the surface and the wrappers are tender.
Drain the dumplings and gently toss them with the prepared chili oil. Serve immediately, garnished with toasted sesame seeds if desired.