Mix all of the meatball ingredients in a large bowl and shape them into desired size.
In a large pan on medium-high heat, heat the oil until it shimmers. Add the meatballs and sear on all sides in batches, then set the seared meatballs aside. They may not be cooked through; they will finish cooking in the sauce.
Once all of the meatballs are seared, prepare the sauce. In a small bowl, mix the cornstarch and water until a slurry forms, and set aside.
In the same pan, add all the sauce ingredients except for the slurry and bring to a light simmer.
Add the seared meatballs to the pan, ensuring they all fit, and top with the cornstarch slurry. Cover and cook for 10 to 15 minutes until the meatballs are cooked through. Then, uncover and let the sauce thicken.
Serve garnished with sesame seeds and scallions.
