Bring a large pot of water to a boil, add the salt for the pasta water, and cook the wide egg noodles according to package directions until just al dente. Drain and set aside.

While the noodles cook, pat the beef sirloin strips dry with paper towels, then season evenly with the kosher salt for seasoning beef and black pepper.

Heat the olive oil in a large deep skillet over medium-high heat. Add the seasoned beef sirloin strips in a single layer (cook in batches if needed) and sear for 2–3 minutes per side until browned but not fully cooked through. Transfer the browned beef to a plate and set aside.

Reduce the heat to medium and add the unsalted butter to the same skillet. Once melted, stir in the finely chopped yellow onion and cook for 3–4 minutes until softened and lightly golden, scraping up any browned bits from the bottom of the pan.

Add the minced garlic to the onions and cook for 30 seconds, stirring constantly, until fragrant but not browned.

Stir in the condensed cream of mushroom soup, low-sodium beef broth, Worcestershire sauce, dried thyme, and paprika. Whisk or stir until the mixture is smooth and well combined, then bring it to a gentle simmer.

Return the seared beef sirloin strips and any accumulated juices to the skillet, stirring to coat them in the mushroom sauce. Simmer gently over medium-low heat for 5–7 minutes, or until the beef is just cooked through and tender.

Reduce the heat to low. Stir the sour cream into the mushroom and beef mixture until fully incorporated and the sauce is creamy. Do not let the sauce boil after adding the sour cream to prevent curdling; warm it gently for 1–2 minutes.

Add the cooked and drained wide egg noodles to the skillet, tossing gently until the noodles are evenly coated in the creamy beef and mushroom sauce.

Sprinkle the chopped fresh parsley over the beef and noodles cream of mushroom, give everything a final gentle toss, and taste to adjust seasoning if needed before serving hot.