Crazy good meatballs

Greek meatballs :)
I've been having an infatuation with greek foods lately and i found these and made them for my mom and I.  AHHHmazing!!

2 lbs hamburger meat (80/20%)
2 large onion
a generous bunch of fresh mint leaves
1 cup of moistened and drained
sourdough bread (crust removed)
2 egg yolks
all purpose flour (not self-rising)
vegetable oil
salt
pepper

Chop onion and mint very finely and combine with hamburger meat. Remove the center portion of the sourdough bread, leaving behind the crust; moisten the bread briefly with milk or water and drain away extra moisture. Place hamburger mixture in a large mixing bowl and add egg yolks, salt, pepper and bread, mixing thoroughly. Let stand for 1 hour and form 2" balls, then coat with flour and fry them in medium hot oil. Turn the balls on all sides until light brown. Remove and drain on a paper towel to absorb excess oil. Serve hot or cold. Best if served next day or later refrigerated. Excellent appetizer if you make smaller balls fondue size.