Set the instant pot to sauté and melt the butter.
Add the garlic and mushrooms and cook for 30-60 seconds.
Add the flour and stir to coat.
Add the chicken broth, stew meat, Worcestershire sauce and dijon mustard.
Cover and seal the pot and pressure cook for 15 minutes.
Quick release.
Season to taste with salt.
Add the egg noodles to the pot and pressure cook for 3 minutes.
Quick release.
Stir in the sour cream.
Serve topped with chopped parsley (optional).