Preheat oven to 425 degrees. In a large bowl, mix together turkey, bread crumbs, basil, oregano, parsley, garlic salt, Parmesan cheese, egg, olive oil, and steak spice. Form meat mixture into 1-1/2" meatballs and place on a greased cookie sheet. Bake for 15 minutes, or until cooked through.
Slice buns in half and place on a baking tray. Place two slices of provolone cheese on the top half of each bun. Preheat oven to broil and lightly toast buns until golden brown and cheese has melted.
Warm marinara sauce in a large saucepan over low-medium heat or in the microwave until heated through.
Top the bottom half of each toasted bun with 3-4 meatballs, cover in marinara sauce and replace the top half of each bun.
Notes
The best bread for meatball subs is based on preference really, but we live to serve these delicious meatball subs on some fresh Italian sub rolls, brioche, or even French bread. You will want bread that can hold up to the sauce and not get soggy.