Pulse the sourdough bread in a food processor and set aside.
Combine all the ingredients in a bowl. Mix well. Take a small ice cream scooper and make golf ball sized meatballs. Roll in your hands and place on to a baking tray. Once complete, place in a 325 degree oven for 25 - 30 minutes.
Serve over cheese polenta, marinara sauce and top with pesto.