In a large pot or Dutch oven, heat the vegetable oil over high heat. Season the chuck roast with salt and pepper on all sides. Once the oil is hot, sear the beef for about 4-5 minutes on each side until browned. Remove the roast and set it aside.
In the same pot, add the quartered onion and sauté for 3-4 minutes until softened. Then, add the minced garlic and sliced ginger, cooking for an additional minute until fragrant.
To the pot, stir in the gochujang, soy sauce, brown sugar, and sesame oil. Mix well to combine, scraping up any browned bits from the bottom of the pot.
Place the seared beef back in the pot and add the beef broth. Bring the mixture to a simmer, ensuring the roast is mostly submerged in the sauce.
Add the chopped carrots, quartered potatoes, and sliced bell pepper into the pot around the roast.
Cover the pot with a lid and reduce the heat to low. Let it cook for about 3-4 hours, or until the beef is tender and easily shreds with a fork.
Once cooked, remove the roast from the pot and let it rest for a few minutes. Shred the beef, and return it to the pot with the vegetables. Stir everything to combine.
Serve the pot roast in bowls, garnished with chopped green onions and sesame seeds.
Notes
Let the roast rest before shredding for best results.