Heat a large saute pan on low to medium-low heat. Toast the fennel seeds and red pepper flake in the pan for one to two minutes, taking care to not burn the spices. Add the olive oil and raise heat on the pan to medium.
Add the diced onion to the saut pan and one pinch of Kosher salt. Sweat onions for 5-6 minutes and add minced garlic. Sweat for another 5-6 minutes. Stir in Italian seasoning, sweat another minute or two and remove from heat and allow to cool to around room temp.
Soak the bread pieces in the milk. In a large mixing bowl, beat the egg with a pinch of salt and a few grinds of black pepper. After the bread pieces have soaked up as much milk as possible, drain the excess and mash the bread with a fork so there are no large or medium sized chunks. Stir the bread and grated parmesan to combine in the large mixing bowl with the beaten egg mixture.
Add cooled onion mixture to bread mixture and stir to combine. Add ground pork and ground beef to the mixture along with the 1/2 TBSP of Kosher salt and 1/2 TBSP of freshly-ground black pepper. It's easiest (for me, anyway) to mix this with your hands. Don't worry about over-mixing. Make sure the entire mixture is as homogeneous as possible.
For Meatballs and pasta: Turn on your oven's broiler and put a rack about 3/4 of the way to the top. Form the meat mixture into 3-4 ounce balls (you'll have about 12-15 meatballs) and place them in a 9x13 roasting pan. Place them under the broiler for about 20 minutes or until the internal temperature is 165F. The inside of the meatball will remain juicy, tender and flavorful. Serve with pasta and marinara and garnish with parmesan cheese.
For "Meatball" Sandwiches: Form the meat mixture into patties. Fry in a pan on the stove top. Melt cheese over the patties. Toast a split hoagie roll. Assemble sandwich with a few tsps of marinara.
