Step 1: Prepare the Beef

1. Pat the chuck roast dry with paper towels, then season all sides with salt and black pepper.
2. Heat a large Dutch oven or heavy-bottomed pan over medium-high heat. Add vegetable oil.
3. Sear the beef on all sides until browned (about 3–4 minutes per side). This enhances the depth of flavor. Remove and set aside.

Step 2: Sauté the Aromatics

1. In the same pan, reduce the heat to medium and add a little more oil if needed.
2. Add chopped onion and sauté for about 3 minutes until translucent.
3. Stir in garlic and ginger, cooking for another minute until fragrant.
4. Add the red curry paste and tomato paste, stirring constantly for about 2 minutes to toast the spices.

Step 3: Build the Sauce

1. Pour in the beef broth and scrape the bottom of the pan to deglaze.
2. Stir in fish sauce, brown sugar, and coconut milk. Mix well to combine.
3. Add lime juice and red pepper flakes if using.

Step 4: Slow Cook the Beef

• Slow Cooker Method: Place the seared beef in the slow cooker and pour the curry sauce over it. Cover and cook on low for 6–8 hours or on high for 4–5 hours.
• Oven Method: Preheat the oven to 300°F (150°C). Return the beef to the Dutch oven, cover with a lid, and bake for 3–4 hours until fork-tender.

Step 5: Shred and Serve

1. Once the beef is tender, use two forks to shred it into bite-sized pieces.
2. Stir the shredded beef into the curry sauce, letting it soak up all the flavors.
3. Serve hot with rice, noodles, or crusty bread, garnished with fresh cilantro, sliced chilies, and lime wedges.