Season beef chunks generously with salt and pepper. Set Instant Pot to sauté mode and heat olive oil. Brown beef chunks in batches, about 3-4 minutes per side. Remove and set aside.
Add onion to the pot and cook for 3 minutes until softened. Add garlic and tomato paste, cooking for 1 minute until fragrant.
Pour in red wine (if using) to deglaze, scraping up any browned bits. Add beef broth, browned beef, potatoes, carrots, celery, bay leaves, thyme, and rosemary.
Secure the Instant Pot lid and set to pressure cook on high for 35 minutes. Allow natural pressure release for 15 minutes, then quick release remaining pressure.
Remove bay leaves. For a thicker stew, set to sauté mode and stir in cornstarch slurry. Simmer for 2-3 minutes until thickened.
Taste and adjust seasoning with salt and pepper. Serve hot with crusty bread or over mashed potatoes.
Notes
Storage tip: Keeps in fridge for up to 4 days. Freezes for up to 3 months (potatoes may become slightly grainy when frozen). For meal prep, portion into individual containers.