Season beef on both sides with kosher salt, black pepper, and garlic powder.
Heat a large skillet with cooking oil over medium-high heat. When oil begins to shimmer, add beef and sear on both sides until deep golden brown, 5 to 6 minutes per side.
Transfer meat to the bowl of a slow cooker (leave skillet over heat).
Reduce heat in the skillet to medium and add butter.
When butter melts, stir in onion, carrots, and garlic. Continue cooking until aromatics are tender, 6 to 8 minutes.
Add Italian seasoning and flour and stir until no dry spots remain.
Slowly pour wine into pan, scraping up any brown bits from the bottom of the pan. Whisk in stock, tomato paste, capers, and vinegar. When liquids begins to simmer, remove from heat.
Pour vegetable and wine mixture around the sides of the beef.
Cover and slow cook on low until roast can be easily shredded with a fork, 8 to 10 hours.
Transfer meat to a cutting board and shred or slice.
Serve meat with cooking liquid drizzled over top.