PREHEAT oven to 350 F. Line a baking sheet with parchment paper.
THOROUGHLY mix the meat, egg, onion, garlic, oregano, salt and pepper in a large bowl. Roll into 15 to 20 meatballs, each about the size of a golfball.
*If you have a food scale, I recommend making each meatball 1 oz in size. It makes it much easier when portioning them out when meal prepping.
SPRAY skillet with cooking spray over medium-high heat. When the skillet is hot, add the meatballs ( may have to be done in batches depending on the size of your pan) Cook for about 30 seconds per side, turning to prevent burning until browned all over, about 5 minutes. Reduce the heat if pan begins to smoke.
TRANSFER the meatballs to the prepares baking sheet. Transfer to the oven to finish cooking for 8 to 10 minutes, until the internal temperature reaches 160 F.
Let the meatballs rest for 5 minutes and serve. Or allow them to cool and store in the refrigerator for up to 4 days.