Preheat oven to 350 degrees. First make your hoisin drizzle by combining hoisin, soy sauce, mirin, fresh ginger, rice wine vinegar, sugar, minced garlic clove, water into a small sauce pan. Bring to boil while stirring constantly. Reduce and simmer for 15-20 minutes until thickened. Remove from heat until ready to serve.
Grate ginger, mince garlic, and chop green onion bottoms and add to ground pork in large glass bowl. Add egg, Panko, salt, mirin, soy sauce and mix with hands until combined. Roll 1 heaping tbsp size balls (1 inch x 1 inch). Then add 2 tbsp vegetable oil (we prefer avocado oil) to your cast iron pan and heat to medium-high. Add meatballs in single layer and cook for approximately 2 1/2 minutes on each side until golden brown. Remove from stovetop and finish in oven for 8-10 minutes. Meanwhile, slice additional onion on a bias and slice ginger into small matchstick pieces. Add 1 tbsp of vegetable oil (avocado oil) to middle of your pan. Heat to high and add onion and ginger. Fry for 45 seconds then quickly remove and drain excess oil. Top meatballs with fried ginger and onions.