in a med bowl, combine the beef, ricotta, raisins, salt, and pepper and mix gently. roll into 40 1-inch meatballs
spray a lrg nonstick skillet and cooking spray and place over med heat. Add the meatballs in batches and brown on all sides, 7 to 8 minutes total. set the meatballs aside on a plate.
Add the onions to the skillet and cook,stirring, until browned, 2 to 3 min. Add the tomato sauce and vinegar and bring to a gentle boil. Return the meatballs to the pan and cook, stirring carefully to coat the sauce, for 5 min, until cooked through. Serve the meatballs in small bowls topped with a generous amount of sauce and a sprinkling of fresh parsley.