Brown the Beef (Optional): Set your Instant Pot to Sauté mode. Add oil and brown beef cubes in batches. Remove and set aside.
Sauté Aromatics: Add sliced onion to the pot and sauté 2–3 minutes. Add garlic and ginger; stir for 30 seconds until fragrant.
Deglaze: Pour in soy sauce, vinegar, and water/broth. Scrape up any brown bits with a wooden spoon.
Add Beef Back In: Add browned (or frozen) beef back to the pot. Stir in brown sugar, sesame oil, and chili flakes (if using).
Pressure Cook: Lock the lid. Set to High Pressure for 45 minutes. Let natural release for at least 15–20 minutes.
Finish: Open lid, shred or break up beef gently with tongs. Optional: Simmer on Sauté mode 5–10 min to reduce liquid slightly. Taste and adjust: more soy for salt, sugar for sweetness, vinegar for brightness.
Serve: Spoon over warm rice. Garnish with sliced scallions, sesame seeds, and optional quick cucumber pickles, kimchi, or steamed bok choy on the side.
