Saucy Meatball Sandwich
Hollowing out the tops of the hoagie buns keeps the sauce from oozing out the sides (though have napkins nearby in case that happens anyway!).
The internal color of a meatball is not a reliable doneness indicator. A beef, veal, lamb, or pork meatball cooked to 160°F is safe, regardless of color. To measure the doneness of a meatball, insert an instant-read thermometer into the center of the meatball.