Mix all of the meatball ingredients except the egg in a large bowl. Season as desired with salt.
Slowly add the beaten egg to bind the mixture (you may not need all of it- too much liquid will make the meatballs soggy).
Shape the mixture into 8 balls.
To assemble:
Heat 1/2 tablespoon of the olive oil in a frying pan over medium heat and add the garlic.
Fry for a few seconds until just starting to brown, then add the tomatoes, basil, oregano, and 250 milliliters (1 cup) water. Season to taste and stir well to combine.
Bring to a boil, then reduce the heat to low and simmer for about 30 minutes, stirring occasionally, until reduced and thick.
Heat the remaining oil in a separate frying pan over medium heat and fry the meatballs, turning often, for 10-15 minutes, until cooked through.
Preheat the grill (broiler) to high.
Slice open the bread rolls and place on a foil-covered baking tray.
Place 4 meatballs into each roll then cover with 1-2 large tablespoons of the tomato sauce.
Place the cheese on top and grill for 3-4 minutes, until the cheese is melted and bubbling.