Add all the ingredients to a large bowl and combine well. (It's easiest to use your clean hands for this)
Form the mixture into balls. You can make them any size you like, just remember that they will shrink a little when cooking and that smaller meatballs will overcook easily if they are small)
Heat a large, non-stick skillet over medium-high heat. Add the meatballs and cook for 1-2 minutes on all sides, just allowing them to brown.
If you are planning on eating them immediately, then add 2-3 cups of marinara to the skillet. Reduce the heat to low, cover and cook for 15-20 minutes or until a meat thermometer reaches 160 degrees when inserted into the center of the meatballs.
If you want to save them for later, OR if you don't want to serve them with marinara, then preheat the oven to 350 degrees and transfer the seared meatballs from the skillet to a baking sheet. Place in preheated oven and bake 15-20 minutes or until a meat thermometer reaches 160 degrees when inserted into the center of a meatball.
To freeze, allow them to cool, then transfer to a freezer safe container and place in the freezer until you are ready to eat them.
Nutrition info for 1 serving: 320 calories, 23g fat, 1g carbs, 0g fiber, 29g protein