Place the bread in a large bowl and add the water. Let it soak for a few minutes and then discard any excess water. Add in the ground beef, onion, egg, garlic, cumin, salt and pepper. Mix well and make sure all the ingredients are well combined.
Wet your hands and form the mixture into football shaped meatballs. You will have 8 to 12 meatballs. Roll the meatballs in all purpose flour and set them aside.
Heat the olive oil in a pan over medium heat. Sear the meatballs in the pan for about 5 minutes until they're golden on all sides. They don't need to be cooked all the way through.
To make the tomato sauce, heat the olive oil in the same pan over medium heat. Once it's shimmery (but not smoking), add in the diced tomatoes, tomato paste, salt, pepper, cinnamon and water. Bring it to a simmer, cover and cook and let it cook for 20-30 minutes so the flavors are combined and the sauce thickens a bit.
Add the seared meatballs to the sauce and let it cook on medium low for about 30 minutes.
If baking in the oven, place the meatballs in an oven safe dish and pour the sauce over the meatballs. Bake at 400 degrees F for 30 minutes. Check after 20 minutes to make sure the sauce hasn't thickened or dried too much. If needed, add 1/2 cup water.
Serve with white rice.