Pat the beef chuck roast dry with paper towels, then cut into bite-sized cubes and season with salt and pepper.

Heat vegetable oil in a Dutch oven over medium-high heat and sear beef cubes for 3-4 minutes on each side.

Lower heat and sauté sliced yellow onion for about 5 minutes until translucent, then add garlic and ginger.

Combine seared beef with aromatics, soy sauce, beef broth, brown sugar, rice vinegar, and red pepper flakes.

Bring to a simmer, cover, and braise on low for 2-3 hours until fork-tender.

Whisk cornstarch with cold water, add to the pot, and cook until the sauce thickens.

Serve over rice or noodles and garnish with cilantro or green onions.