When I lived in Ankeny, Iowa, we used to go north a few miles to a restaurant called "The Fjord." They served wonderful Scandinavian food. One of my favorites was Swedish Meatballs. My mom learned to make this wonderful dish, and they were often seen at our church potlucks.
In a large bowl, mix the ground beef, ground pork, chopped onion, cracker crumbs, allspice and cloves.
Once all those ingredients are mixed, slowly add in the milk (it's easiest to this part with your hands...I wear latex gloves).
Add a few shakes of salt and pepper.
Using a tablespoon, roll the meat mixture into balls about the size of large walnuts.
Place the meatballs in a 9x13 pan.
Make the sauce:
In a large saucepan, combine the brown sugar, vinegar, water and mustard.
Over medium heat, bring the ingredients to a boil.
Pour the sauce over the meatballs.
Bake the meatballs for one hour.
If you wish, you can make a lot of meatballs and just use what you need without adding the sauce to all of them. Next, you can freeze the remaining un-sauced meatballs, and next time you want to use them, simply thaw them and make more sauce. Pour the sauce over the thawed meatballs and bake at 350 for one hour as above.