Set your Instant Pot to sauté mode and melt the butter over medium-high heat until foaming. While the butter melts, pat the beef chunks dry with paper towels—this ensures proper browning and develops deeper flavor. Working in batches to avoid overcrowding, brown the beef on all sides until a golden crust forms (about 2-3 minutes per batch). Season with salt and pepper as you go. Remove the seared beef and set aside; this step creates the flavorful fond that will anchor your entire dish.

In the same pot with the browned butter and fond, add the minced garlic and sliced mushrooms, stirring for about 1 minute until fragrant. Sprinkle the flour over the mixture and stir constantly for 1-2 minutes to create a roux that coats all the ingredients—this will thicken your sauce and add body. Pour in the 3 cups of beef broth and worcestershire sauce, scraping the bottom of the pot to release all the flavorful browned bits.

Return the seared beef to the pot along with the smoked paprika, stirring to combine everything evenly. Lock the lid and set the Instant Pot to high pressure for 15 minutes. When the timer beeps, perform a quick release by carefully moving the valve to venting. Open the lid and check that the beef is fork-tender; the meat should easily break apart when pressed.

Stir the egg pasta directly into the pot with the beef and sauce. Lock the lid again and pressure cook on high for 3 minutes—this timing ensures the pasta cooks to al dente without becoming mushy. Perform another quick release when done, and stir the pasta to separate any strands that may have stuck together.

Turn off the sauté mode and stir in the full-fat sour cream, which creates a luxurious, silky texture that truly elevates stroganoff. Taste and adjust seasoning with salt and pepper as needed. If you prefer a thicker sauce, mix the corn starch with the ¼ cup beef broth to create a slurry, then switch to sauté mode and add this mixture while stirring constantly until the sauce reaches your desired thickness—I find this gives a glossy, restaurant-quality finish.

Ladle the beef stroganoff into bowls or over rice if desired, and serve immediately while the dish is hot and creamy. The stroganoff will maintain its best texture for about 15-20 minutes after finishing.