Preheat oven to 400°F and drizzle avocado oil in a 9x13 baking dish.
In a bowl, mix beef, egg, coconut aminos, arrowroot, ginger, garlic, salt, pepper, and green onion until just combined.
Shape into 1.5-inch balls and place in dish. Bake for 20 minutes, until cooked through.
Whisk sesame oil, coconut aminos, rice vinegar, fish sauce, arrowroot, broth, ketchup, and cayenne in a small bowl.
Remove meatballs, discard fat, and wipe dish.
Return meatballs, pour sauce over, and bake for another 8 minutes until thickened.
See full steps with tips & photos → https://theboatshedcafe.com/baked-mongolian-beef-meatballs/