Turn the Instant Pot to Sauté mode and season beef with salt and pepper.
Sear beef in batches until browned on all sides, then remove and set aside.
Add onions to the pot and sauté until softened, about 2–3 minutes.
Stir in garlic and cook for 30 seconds until fragrant.
Add tomato paste and stir to coat the onions and garlic.
Return beef to the pot and pour in beef broth.
Add Worcestershire sauce, carrots, potatoes, parsley, and oregano.
Stir everything together, scraping the bottom to release browned bits.
Close the lid, seal the valve, and cook on Manual/High Pressure for 30 minutes.
Allow a natural release for 10 minutes, then quick-release the remaining pressure.
Mix flour and water in a small bowl to form a slurry.
Turn on Sauté mode again and stir in the slurry to thicken the stew.
Add frozen peas and corn, stirring until warmed through.
Simmer 2–3 minutes until thickened to your liking.
Taste and adjust seasonings before serving.