In a large bowl mix together the ground beef, breadcrumbs, milk, minced garlic, pepper, salt, Worcestershire sauce and red onion. Mix until all of the ingredients are combined.
Roll the meat mixture into meatballs (golf ball sized balls or 2-inch balls) and set on a baking sheet in a single layer
Heat 2 tbsp of avocado oil (or olive oil) in a large skillet or cast iron skillet on the stove top. Cook the meatballs for 3 minutes on each side until they’re browned. There is no need to cook all the way through.
Once you have browned all of the meatballs, transfer them to the crockpot using a slotted spoon.
In a large bowl mix together the beef stock, heavy cream, Dijon mustard, soy sauce, salt and pepper. Pour over the meatballs.
Cook on low heat for 4 ½ hours or on high for 3 hours.
30 minutes before serving you’ll finish the sauce. Mix the 3 tbsp of flour with the 3 tbsp of water. Stir well making sure there aren’t any clumps.
Add the flour mixture into the crockpot and stir. Place the lid back on top and cook on high for an addition 15-25 minutes or until the sauce has thickened up.
Serve the Swedish meatballs and gravy over mashed potatoes or noodles.