Combine all of the ingredients in a food processor. Form mixture into meatballs (you can use cookie scoop). Chill at least 1 hour and up to overnight.
Heat vegetable oil in a large skillet over medium high. Add meatballs and cook until browned and cooked through. Set aside.
Teriyaki sauce: In a small pot, combine all ingredients for teriyaki sauce, except sake and cornstarch. Cook on medium-high heat until warm and add sake and cornstarch. Bring to a boil while whisking constantly until dissolved and desired thickness is reached. Do not leave unattended and set aside when done.
Return meatballs to skillet, toss to coat. Serve immediately, topped with sesame seeds.