Cook meatballs according to package directions.
Melt butter in a large frying pan over medium heat. Add peppers and pineapple and sauté until bell pepper is tender, approximately 5 minutes. Add cooked meatballs and reduce heat.
In the meantime, combine chicken broth, teriyaki sauce, sirachi, sugar and cornstarch in a bowl. Whisk until well combined.
Pour sauce over meatball mixture in the frying pan. Stir until well combined. Increase heat until the sauce begins to boil, stirring continuously.
Once a slow, rolling boil begins, remove pan from heat. Stir until sauce is thick and has glazed the meatballs, pineapple and peppers.
Place 3 meatballs and a spoonful of the pepper / pineapple mixture on each mini sub roll. Top and serve warm.