Generously salt chuck roast on all sides and dust with flour. Heat vegetable oil in instant pot on Sauté function and sear chuck roast until browned on all sides, then remove and set aside
Add butter and onions to the instant pot and sauté until caramelized, about 40 minutes, stirring every 5 minutes
Deglaze the pan with wine and beef broth, then add garlic, Worcestershire sauce, and Dijon mustard. Add chuck roast back into the pot, season with salt, thyme, and pepper
Cover with lid and pressure cook on low for 1 hour until meat is falling apart
Serve with roasted potatoes, mashed potatoes, or crusty bread
