Spray Instant Pot interior with cooking spray. Set to saute.: The initial aroma of hot oil and the faint hiss as the surface warms signals readiness, and this step primes the pot for proper browning which is essential for flavor development. If the pot feels cool, give it another minute so the surface sizzles when you add ingredients. A common mistake is rushing into adding meat to a cool surface, which causes steaming instead of browning.
Brown ground beef, onion, and garlic.: You will hear a steady sizzle as the ground beef hits the hot pot and begin to smell rich, caramelized notes; the onion will soften and turn translucent while the garlic offers a bright aromatic lift. Browning forms fond, those brown bits that add deep flavor when deglazed. Avoid crowding the pot and stirring constantly, which prevents proper browning and results in pale meat.
After beef is browned stir in flour.: At this point the flour dusted into the hot mixture will absorb fat and steam slightly, creating a nutty, toasty scent that helps thicken the eventual sauce. The flour needs a short moment of cooking to lose any raw taste and to bind with the fats. Not cooking the flour long enough can leave a pasty texture in the gravy, so give it a brief stir until it smells faintly nutty.
Add broth, soup, and salt and pepper. Mix.: When the beef broth hits the pot you will hear a louder simmer and see the browned bits lift from the bottom, which is important for integrating flavor. The canned cream of mushroom soup dissolves into the liquid, creating a glossy, fragrant base. Stir thoroughly to prevent lumps and to evenly distribute seasoning. A typical error is not scraping the bottom well, which risks stuck bits and uneven flavor.
Add noodles.: As you scatter the uncooked egg noodles into the simmering mixture you will notice them sitting in the glossy liquid, ready to swell and absorb savory flavor. Distribute them so they are mostly submerged to ensure even cooking. If some noodles float and dry out, press them gently into the broth; leaving them exposed can lead to uneven cooking.
Place lid on Instant Pot.: The lid seals with a reassuring click and the sound of escaping steam will stop, indicating the pot is building pressure. This sealed environment concentrates flavors and cooks the noodles quickly. Make sure the valve is set correctly; forgetting to seal properly will prevent pressure buildup and undercooked pasta.
Set to high pressure for 8 minutes.: During the pressure phase the pot becomes quiet, and the aroma intensifies as the beef and broth marry. The time chosen ensures the egg noodles cook through while absorbing sauce, yielding tender but not mushy texture. A common misstep is overcooking with too long a time, which can create a gummy noodle texture.
After it is done, let the pressure naturally release for about five minutes, and then change to quick release until all the pressure is gone.: The initial natural release allows some gentle settling and prevents violent bubbling when you quick release; you may hear soft hisses and see a little steam, and the pot will relax. Quick releasing afterwards depressurizes the unit so you can safely open the lid. Avoid forcing the lid early, and be careful of hot steam when using quick release.
Stir in sour cream until combined.: Once you open the pot and the movement of steam has subsided, the cool, tangy sour cream should be folded in off heat, bringing a creamy sheen and slightly bright finish to the sauce. You will notice the texture mellow and thicken as the dairy blends. If added while the pot is still vigorously boiling the sour cream can break, so temper it by stirring gently and off heat for the smoothest result.