I've been making meatballs for more than 20 years now. I learned from my first wife who learned from her mother. I've made a few adjustments over the years and for the first time have written down a recipe so I can produce the same result consistently.
I often had a problem with the meatballs falling apart. The secret is the right amount of binder (eggs and bread crumbs), but I also found it helped to omit chopped onions and use onion powder or granules instead.
There are 66 cute little meatballs cooking as I write.
Italian Meatballs recipe
4 pounds chopped beef, 85% lean
2 tablespoons onion granules or powder
2 tablespoons garlic granules or powder
2 tablespoons dried parsley
3 tablespoons dried oregano
2 teaspoons salt
2 teaspoons black pepper
4 large eggs
1 cup fine bread crumbs
Combine all ingredients well in a large bowl. Use your hands!
This recipe assumes you have lots of tomato sauce going -- I would make a smooth sauce using two 28-ounce cans of crushed tomatoes or puree. You just need to get it started simmering.
Roll into balls. I like them about 1-1/2" diameter.
Heat some olive oil in a large frying pan and brown the balls on all sides. Do not overcrowd the pan. Do them in shifts. For this size ball, about a dozen in a large pan at a time is good. Turn them gently with a tablespoon.
Gently lower the balls into the sauce and cook for at least an hour, preferably up to two hours so that meatballs are infused with the tomato flavor. I've had meatballs at too many Italian joints that were not cooked in the sauce, but only covered with it.
Too many leftovers? Freeze them!