Combine the ground chicken, salt, sesame oil, scallions, and shallot in a large bowl. Use a microplane to grate the dried shiitake onto the meatball mixture.
Knead the mixture very thoroughly with your hands. The final texture should be sticky and tacky.
Fry up a tiny patty and taste it for seasoning. Adjust with additional salt if needed.
Cover the bowl and chill the meatball mixture in the fridge for at least an hour and up to a day. Chilling the mixture will make it easier to roll out your meatballs, but if you don’t have time, just make them right away.
When you’re ready to cook the meatballs, turn on the broiler and arrange the oven rack so that it’s 6 inches from the heating element. While the oven heats up, brush a rimmed baking sheet or broiler pan with avocado oil.
Scoop out 24 meatballs with a #40 disher (~1½ tablespoons) and roll them into uniform size balls with your hands. (If you add avocado oil to your hands, the meatballs won’t stick!) Arrange the chicken meatballs evenly on the greased baking sheet.
Broil the meatballs for 2 minutes, and then brush them with All-Purpose Stir-Fry Sauce. Rotate the tray 180 degrees.
Repeat the above step twice more so that the meatballs are cooked for a grand total of 8 minutes (not including basting time) and the meatballs are basted with the sauce three times.
The meatballs are finished cooking when the tops are browned and cooked through. Make sure they don’t burn or get overcooked. (The final internal temperature should be 165°F.)
Top with toasted sesame seeds if desired. Serve immediately!