Add all ingredients EXCEPT for the oil to a large bowl. Knead very well (best with the hook attachment of a handheld mixer) until a smooth "dough" forms.
Using 1 heaping teaspoon of meat mixture, shape a small and firm meatball between the palms of your hands. Repeat until you've used all the mixture.
Heat the oil in a large skillet over medium-high heat. Working in batches, brown the meatballs until cooked all the way through. Remove from the pan and set aside.
Make the sauce:
Whisk together all ingredients for the sauce in a medium bowl.
Cook the meatballs:
Combine the meatballs and sauce in a 4-5 quart slow cooker. Cook on HIGH for 2-3 hours, then remove the lid and finish cooking uncovered for 30 minutes or until the sauce has thickened.
Notes
Serves 3-4 as a main or 6-8 as an appetizer (depending on other dishes served and how big your appetites are).