Season beef with salt and pepper. With the instant pot set to saute, add olive oil and brown beef on both sides in batches. Set aside and saute onion, garlic and peppers for 1-2 minutes.
Add 6 Tbsp beef broth, soy sauce, brown sugar, sesame oil, and red pepper flakes to the pot. Stir until sugar is dissolved.
Add browned beef and any accumulated juices. Select High Pressure. Set timer for 12 minutes.
In the meantime, steam broccoli on the stove top or in the microwave until just tender.
When timer goes off turn pressure cooker off and use quick pressure release. When valve drops carefully remove the lid.
In a cup combine cornstarch and remaining beef broth; stir until smooth. Add to pressure cooker pot. Stir well to combine. Select browning or saute and stir until sauce comes to a boil and thickens. Add steamed broccoli.
Serve over hot, cooked rice and garnish with sesame seeds.