Set pressure cooker to SAUTE and drizzle with 1 tablespoon oil.
Rub 1 tablespoon of oil all over the beef, then season with salt and pepper.
Use tongs to arrange the beef in the pot. Sear for about 2 minutes, then turn and continue to sear on all sides until browned all over.
Add beef broth, soy sauce, worcestershire sauce, onions, garlic powder, onion powder, and dried herbs.
Place lid on the pot and slide into the locked position. Turn vent valve to SEALED position.
Set pot to MANUAL or PRESSURE COOK for 60 minutes. (see note if using a frozen roast)
Once cook time is up, do nothing while the pot naturally depressurizes for 15 minutes. Mean while preheat oven to 375 degrees.
Turn knob to VENTING position and remove lid once float valve drops.
Transfer meat to a large cutting board. Slice against the grain, or shred with two forks into chunks (don't shred it too finely, see note). Pour 1 cup of the juices from the pot over the beef to keep it really moist.
Line a baking sheet with the bottom half of the buns. Top each with a slice of cheese. Divide the meat between the buns. Top with another slice of cheese and the top of the bun.
In a small bowl stir together butter, dijon mustard, and garlic powder. Brush over the tops of the buns. Sprinkle with sesame seeds if desired.
Cover loosely with foil and bake for 10 minutes until cheese is completely melted. Remove foil and bake another 3-5 minutes until buns are lightly toasted. While sandwiches are baking, prepare au jus sauce. Serve with au jus sauce for dipping.