Setup 6-qt pressure cooker. Select the “Sauté” setting. Heat oil and add chuck roast to pressure cooker. Season with kosher salt and ground pepper. Sear both sides of meat for about 2-3 minutes on each side. Remove meat and transfer to a plate. Set aside.
Add a little more oil then add onion. Cook until translucent about 3 minutes. Mix in garlic and tomato paste, about 2 minutes.
Add beef broth, Worcestershire sauce, thyme, rosemary, bay leaves and potatoes. Mix until well combined. Transfer roast to pressure and place meat on top of vegetables.
Put lid on and select the “Manual” setting and adjust pressure to “high”. Set time for 45 minutes. Set spout to “Sealing” not “Venting”.
After finished, do a “quick-release” according to manufacturer’s instructions. Add carrots and celery. Put lid back on pressure cook. Select “Manual” setting and adjust to “high”. Set time for 10 minutes. Set spout again to “Sealing” not “Venting”.
Remove beef and vegetables from pressure cooker. Shred meat with two forks.
In a small bowl, mix together 1/4 cup water and cornstarch. Add cornstarch mixture to pressure cooker. Select “Sauté” setting and bring gravy to a boil, about 3-4 minutes.
Serve meat immediately with vegetables. Top with gravy. Garnish with fresh herbs, if desired.