In a large Dutch oven over medium high heat sear roast on each side about 8 min per side. Cook until you have a nicely browned crust.
Remove meat and set aside. Deglaze your pan with finely diced onion and a small amount of water. Return roast to pot.
Add water to cover. Mix in bouillon, salt, and garlic salt. Place the bay leaves, peppercorns, oregano, and rosemary in a coffee filter and secure tightly with kitchen string. Add this to the pot.
Bring to a boil over high heat, then reduce heat to low, cover with a lid, and simmer for 6 to 8 hours. Remove coffee filter and discard. Remove roast from the pot and shred with two forks. Reserve broth for dipping if desired.
Slow Cook:
You can also put this in your slow cooker on low. Sear in a skillet on the stove. Add all ingredients to pot and cook for 8-10 hours.
Instant Pot:
Use Saute to sear your meat on each side 6-8 min on the High or More mode. Remove roast. Add water to pot and deglaze the bottom. Add roast back in. Add bouillon, salt and garlic salt. Then add your sachet. Cook roast for 75-90 min with a full NPR.
To Assemble Sandwiches:
Take your hoagie buns and slice them. Then butter each side of the bun and brown in a skillet or under a broiler.
To assemble the sandwich, add meat and cheese to each sandwich. Serve with extra meat juices and giardiniera on the side.