To a large bowl, add ground chicken, parmesan, onion, garlic, Italian seasoning, red wine vinegar, salt and pepper. Mix to combine.
Use a 1 Tablespoon-sized cookie scoop (or a spoon) to make 30 meatballs. Coat hands with a small amount of oil, then gently roll and round each meatball and place on a parchment-lined baking tray.
If time allows, chill meatballs for 30 (or more) minutes.
In a large skillet over medium-high heat, add oil and heat until shimmering. Add meatballs and turn the heat down after about 3 minutes. Continue cooking for another 7-9 minutes until browned, or until an instant-read thermometer reads 165˚F.
Notes
To bake instead of pan fry: Preheat oven to 400˚F for 18-22 minutes, or until meatballs reach an internal temperature of 165˚F.