Prepare a baking sheet with parchment paper. Preheat oven to 400 degrees F.
Chop onions and garlic. I used a food processor to chop them finely.
In a large bowl, whisk eggs. Add garlic and onions. Add meatball seasoning ( not sauce ingredients ).
Stir in bread crumbs and parmesan cheese. Whisk to combine egg/seasoning mixture well.
Add in ground beef. Using your hands, work the ground beef into the wet mixture, coating everything well.
Form even size meatballs with a cookie scoop then place on prepared baking sheet close together, but not touching each other.
Bake meatballs for 35 minutes. then transfer to cooling rack while baking the rest.
To make the sauce, whisk together 1 tablespoon cornstarch and 1 tablespoon cold water. Add sauce ingredients; soy sauce, honey, ketchup, sesame oil, rice vinegar, ginger red pepper flakes, black pepper, and sugar then whisk well to combine.
Add meatballs to slow cooker. Pour sauce over meatballs.
Cover and cook on low for about 1-2 hours.
Set slow cooker to high for about an hour. This will thicken the sauce.
Serve meatballs with chopped green onions, sesame seeds and with cooked rice.
***SEE NOTES FOR FASTER ALTERNATIVE