The Hard Sear
Pat chunks of flank steak dry. Season generously on all sides with kosher salt and black pepper. Heat 1 tablespoon of vegetable oil in a large Dutch oven over medium-high heat. Sear the beef in batches until a deep, dark brown crust forms on both sides. Remove meat and set aside.
Searing creates a complex layer of flavor through the Maillard reaction that boiling simply cannot replicate, building the foundational depth of the sauce.
A rich, mahogany-brown crust on the meat without letting the bottom of the pot burn black.