Place the bread in a large bowl and cover with water. Set aside for about 10 minutes while you chop the onion and herbs.
Drain the water from the bowl with the bread. Take handfuls of the bread and squeeze out as much water as possible over the sink. Place wet bread back in the bowl and add the pork, beef, egg, onion, garlic, mint, parsley, oregano, salt and pepper. With your hands, mix all of the ingredients together thoroughly until well combined. Place in the fridge, covered, for 30 minutes to an hour (this isn't absolutely necessary, but it allows the flavours to develop and also makes the meatballs easier to form. You could also let it sit in the fridge overnight).
Preheat the oven to 200 C. Prepare baking trays by covering with baking paper.
Place the flour in a shallow plate. Take the meatball mixture from the fridge and form the meatballs: Roll the mixture into 2 to 3cm balls, flatten into a disk shape, then coat lightly in flour, shaking off any excess. Place the meatballs on the baking tray.
Bake in the preheated oven for approximately 30 to 40 minutes, turning over once halfway through. The meatballs should be done on the inside and crispy on the outside.
Serve immediately or at room temperature.
These meatballs are perfect for freezing, either before or after baking. To freeze before baking, form into disks and freeze without coating in flour.
One of my favourite Greek dishes actually calls for leftover meatballs. Simply saute some chopped onion in olive oil till translucent. Add meatballs, tomato puree or passata, a pinch of ground cinnamon, oregano, salt and pepper, and simmer on medium high till most of the water is evaporated and the olive oil comes to the surface. Serve with rice or potatoes.