Warm a large pot over medium-high heat, add seasoned beef strips in a single layer, and sear 3–4 minutes until caramelized edges form. Transfer beef to a plate.

In the same pot, toss in sliced mushrooms and chopped onions. Cook 5 minutes, stirring occasionally, until onions turn translucent and mushrooms release golden juices.

Add minced garlic and paprika, cooking 1 minute until fragrant. Stir constantly to meld that warm, smoky color and aroma throughout the mixture.

Sprinkle flour evenly over the veggies and beef bits, stirring well to coat. Cook 1–2 minutes until the flour turns a light golden hue.

Slowly whisk in beef broth and Dijon mustard, scraping up any browned bits from the pot bottom. Bring mixture to a gentle simmer.

Nestle egg noodles into the simmering liquid, cover, and reduce heat to medium-low. Cook 10–12 minutes, stirring halfway, until noodles are tender.

Remove the pot from heat, then gently fold in sour cream until silky smooth. Season with salt and pepper to taste.

Sprinkle chopped parsley over the stroganoff, ladle into bowls, and serve immediately.