Brown the Beef: Heat the oil in a large deep pot or Dutch oven over medium-high heat. Add the ground beef and ¼ teaspoon of the salt. Cook for 5-6 minutes, breaking it into crumbles, until well browned. Drain any excess fat and transfer the beef to a plate.
Tip: Let the meat sit undisturbed for the first 3 minutes to develop a good crust before breaking it up.
Cook the Vegetables: Return the pot to medium heat and add the butter. Once melted, add the onion, mushrooms and ¼ teaspoon of salt.
Cook for 5-6 minutes, stirring occasionally, until the onion is softened and the mushrooms are golden and have released their liquid. Add the garlic and cook for 1 minute until fragrant.
Make the Sauce: Sprinkle the flour over the vegetables and stir to coat evenly. Cook for 1 minute, stirring constantly, until the flour smells slightly nutty.
Pour in the beef broth gradually, stirring constantly to prevent lumps. Add the 1 tablespoon of the Worcestershire sauce, Dijon mustard, ½ teaspoon of salt, and black pepper and stir to combine. Return the beef to the skillet.
Add the Noodles: Add the dry egg noodles to the skillet and stir to submerge. Bring to a boil, then reduce to a steady simmer.
Cover and cook for 8-10 minutes, stirring every couple of minutes, until the noodles are tender and have absorbed most of the liquid.
Tip: Add a splash of broth if the mixture looks too dry before the noodles are done.
Finish: Remove from heat. Let the stroganoff sit for 2 minutes to cool slightly, then stir in 1 tablespoon of Worcestershire sauce and the sour cream until smooth and creamy (adding it off heat and after a brief rest prevents it from curdling).
Stir in the parsley, then taste for seasoning and adjust with salt and pepper as needed.
Notes
Make sure you use a large, heavy bottom pot with a lid for this recipe, since everything cooks in one-pot you want to make sure there’s room for everything.
Don't skip the resting step before adding the sour cream, even a couple of minutes off heat makes a big difference in preventing the sauce from breaking.
If you're iffy on Worcestershire sauce, taste the final dish at the end before adding the second tablespoon. I personally feel like adding and extra tablespoon at the end wakes the flavors up and adds extra flavor, but if you're more of a traditionalist when it comes to stroganoff flavors, taste first and skip it that's more your vibe.
I've tested this beef stroganoff with greek yogurt and it works quite well. Make sure it's a thick Greek yogurt, low-fat or whole, fat-free was not my favorite, and make sure to let the pasta rest per the instructions, as yogurt has a higher chance of separating than sour cream.