Preheat oven to 375º
Place the bread pieces in a small bowl and pour over the milk so the bread can absorb it.
Heat Olive Oil in a small sauté pan over medium heat.
Add Onions and Bell pepper to the hot pan and sauté until the onions begin to get translucent.
Add garlic to pan and turn off the heat.
Cool veggies slightly.
Combine Beef, Veggies and the rest of the ingredients, except for the sauce, in a large bowl and mix well.
Make meatballs out of the prepared meat.
Place meatballs in a lightly greased casserole dish.
Add sauce to meatballs making sure they are at least half covered.
Cook meatballs uncovered for 30 minutes.
Add shredded Mozzarella cheese to the meatballs during the last 5 minutes of cooking time, if desired.
Serve meatballs and sauce with a tossed salad or over gluten free pasta.