Preheat oven to 400 degrees.
Add your onion, bell pepper, and garlic to food processor and pulse until diced.
Add meat, vinegar, Italian seasoning, salt, pepper, and parsley. Give a couple of quick pulses to combine.
In a bowl combine water, cream of tartar, and baking soda. When it stops fizzing add to meat mixture.
Roll meat into balls.
Place on baking sheet and cook for about 15 minutes.
Add meatballs to spaghetti sauce and keep warm.
Reduce oven temperature to 350 degrees.
Cut spaghetti squash in half and place face down on a baking sheet.
Bake for 30 minutes
Let cool for a few minutes, scoop seeds out and use a fork to pull the squash from the edges.
Serve with sauce and meatballs.