2) In a medium bowl, pour the milk over the breadcrumbs and leave to soak for 5 minutes. Remove the bread from the milk and squeeze out excess milk, until the bread is moist but not soggy.
3) In a large bowl, mix together the beef, pork sausage, soaked bread, cooled vegetables, basil, oregano, parsley, pepper, chilli flakes, grated Parmesan and egg. Gently roll into 5cm balls.
4) Heat the same large saute pan used for the vegetables over a medium heat and add 1 tbsp oil. Cook the meatballs, browning completely until the internal temperature reaches 74C, using an instant-read thermometer.
5) Meanwhile, remove the insides from the hoagie rolls. To assemble the heroes, fill the hoagies with 4 meatballs each. Drizzle with 60ml marinara sauce and top with 3 slices of mozzarella cheese.
6) Place the heroes on a sheet pan under the grill until the cheese melts and turns golden brown. Top each sandwich with 1/2 tbsp Parmesan.
1) In a medium saucepan heat the olive oil, add the onions and cook over a medium to low heat until the onions are transparent.
2) Add the garlic and cook until almost brown, then add the tomatoes. Cook for 1/2 hour over low to medium heat, then add the basil and oregano and continue to cook for 30 minutes longer.
3) Place in a food mill or a blender and puree into a sauce. Season with salt and pepper, to taste.