Add the avocado oil, onion, carrot, and garlic into the slow cooker. Saute for 5 minutes (if your slow cooker has a saute mode, if not - just add the ingredients in the slow cooker).
Next, add the tomato paste, salt, pepper, red pepper flakes, and crushed tomatoes to the slow cooker and stir until everything is combined.
In a mixing bowl, add the ground beef, pork, breadcrumbs, milk, eggs, garlic, parsley, parmesan, salt and pepper. Use a dough hook to stir together the meat mixture until just combined. Use a large ice cream scooper to create roughly 18 meatballs.
Place the meatballs into the tomato sauce in the slow cooker. Cover and cook on low for 6-8 hours or on high for 4-5 hours.
After cooking, skim off any fat from the surface and sprinkle with fresh basil and parmesan.
Serve on its own with crusty bread or over a bed of pasta.
