Marinara: In a large pot, heat 1/4 cup olive oil over medium heat.
When the oil is shimmering, add onions and sauté over medium-low heat until the onions are translucent and softening about 10 minutes.
Add garlic, celery, carrot, and 1/2 teaspoon each of salt and pepper. Sauté for 8 to 10 minutes or until everything is soft.
Add the tomatoes, bay leaf, and wine, reduce the heat under the pot to low, and simmer for 25 to 30 minutes.
After 25 or 30 minutes, add red pepper and brown sugar and cook for an additional 30 minutes. Remove and discard bay leaves. Let marinara cool to room temperature, then cover and refrigerate.
The sauce will be chunky but when it is cool you can add to a blender or food processor to thin the texture of the sauce.
Meatballs: In a medium pan, add 1 tablespoon olive oil over medium heat. When oil is shimmering, add diced onions and cook for about 8 to 10 minutes until the onions are soft.
After 8 to 10 minutes add garlic, stir it in with the onions and cook for another two minutes. Remove pan from heat and allow garlic and onions to cool.
Pre-heat oven to 400 degrees F.
In a large bowl, combine all ingredients including the cooled onions and garlic. With clean hands, mix everything together so that all ingredients are combined very well with the ground beef.
Again, with your hands, pull off hunks of the ground beef mixture and roll them into balls that are about 1.5 inches across. With 2 pounds of meat, you should get close to 24 meatballs.
Add all meatballs to a parchment-lined sheet pan, leaving some space between each meatball.
Once the oven has reached 400 F, cook the meatballs for 20 to 24 minutes. If you have a digital thermometer, you want to make sure the meatballs get to 160 degrees F to be completely cooked through.
Sandwich assembly: pre-heat oven to 350 degrees F.
Add marinara and cooked meatballs to a large pan over medium-high heat and simmer to warm everything up for about 5 to 10 minutes.
Slice each bread rolls lengthwise 2/3rds of the way through the bread and open the rolls up like a hinge.
Slice bread into six-inch rolls.
Add 3 meatballs for every six inches of bread, top with more sauce and top the meatballs with slices of the provolone cheese. Close the sandwich and add each meatball, sauce and cheese filled sandwich to a sheet pan
Add pan with meatball subs to oven 350 degrees for 5 minutes to melt the provolone and warm everything through.
Sprinkle extra parmesan cheese on the saucy parts of each sandwich. Serve and enjoy.