Whisk broth, soy sauce, brown sugar, rice vinegar, hoisin, sesame oil, red pepper, and black pepper in a bowl.
Set Instant Pot to Sauté. Warm the oil until shimmering.
Brown the beef in two batches, 3–4 minutes per batch. Transfer to a plate.
Sauté onion for 2 minutes. Stir in garlic and ginger; cook 30 seconds until fragrant.
Splash in 2–3 tablespoons of the sauce to deglaze, scraping up browned bits.
Return beef and any juices. Pour in remaining sauce. Lock lid and set to High Pressure for 30 minutes.
Let pressure release naturally for 10 minutes, then quick-release any remaining steam.
Mix cornstarch with cold water. Switch to Sauté, stir in slurry, and simmer until thickened, 2–3 minutes.
Fold in broccoli and cook until crisp-tender, 2–3 minutes. Season with salt to taste.
Stir in green onions. Top with sesame seeds and serve over rice or noodles.