Prep the beef and broccoli. Slice the beef thinly against the grain. Cut broccoli into similar-sized florets. Mince the garlic and grate the ginger. Have everything ready—this moves fast.

Whisk the sauce base. In a bowl, combine soy sauce, beef broth, brown sugar, rice vinegar, sesame oil, and red pepper flakes. Stir until the sugar dissolves. Set aside.

Sauté the aromatics. Set the Instant Pot to Sauté (Normal). Add oil, then garlic and ginger. Cook for 30–45 seconds until fragrant. Do not burn—stir constantly.

Brown the beef lightly. Add beef in two batches, stirring for 1–2 minutes per batch until it loses its raw pink edges. You’re not cooking it through—just getting a little color. Return all beef to the pot.

Deglaze. Pour in 2–3 tablespoons of the sauce and scrape up any browned bits from the bottom with a wooden spoon. Make sure the bottom is clear to avoid a burn warning.

Add the rest of the sauce. Pour in the remaining sauce mixture and stir to coat the beef evenly.

Pressure cook. Cancel Sauté. Seal the lid and set to Manual/Pressure Cook on High for 5 minutes. The pot will take a few minutes to come to pressure.

Quick release. When the timer ends, carefully perform a quick release. Open the lid and give it a stir.

Thicken the sauce. Turn Sauté back on. In a small bowl, whisk cornstarch with water to make a slurry. Stir the slurry into the pot and simmer 1–2 minutes until the sauce looks glossy and slightly thick. It will continue to thicken as it cools.

Steam the broccoli. Add broccoli florets directly to the pot. Stir to coat. Cover with the lid (no pressure) and let the residual heat steam the broccoli for 3–5 minutes, until crisp-tender. If you prefer softer broccoli, cook 1–2 minutes longer.

Taste and adjust. Add more soy sauce for salt, a splash of vinegar for brightness, or a pinch of sugar if you want it sweeter. Turn off Sauté.

Garnish and serve. Top with sliced green onions and sesame seeds, if using. Serve hot over steamed rice.